a commercial refrigerator with r-134a as the working fluid is used to keep the refrigerated space at -29 0c by rejecting its waste heat to cooling water that enters the condenser at 16 0c at a rate of 0.22 kg/s and leaves at 28 0c. the refrigerant enters the condenser at 1.2 mpa and 65 0c and leaves at 42 0c. the inlet state of the compressor is 60 kpa and -34 0c and the compressor is estimated to gain a net heat of 450 w from the surroundings. take the enthalpy at state 3 as the hf at operating temperature. determine the following; (1) the quality of the refrigerant at evaporator inlet. (2) the mass flow rate of the refrigerant. kg/s (3) net compressor power input. kw (4) the refrigeration load. kw (5) the cop of the refrigerator. (6) the theoretical maximum refrigeration load for the same power input to the compressor. kw hint: to find the theoretical maximum refrigeration load first find the maximum cop of the refrigerator for the same temperature limits based on reversed carnot cycle.
Answers
To solve this refrigerated problem, we can use the thermodynamic properties of R-134a from the data. Let's denote the states as follows:
State 1: Inlet to the compressor
State 2: Outlet of the compressor, inlet to the condenser
State 3: Outlet of the condenser, inlet to the evaporator
State 4: Outlet of the evaporator, inlet to the compressor.
We are given the following information:
T1 = -34°C
p1 = 60 kPa
T2 = 42°C
p2 = 1.2 MPa
T3 = -29°C
T4 = -34°C
m_dot = 0.22 kg/s
Tcw1 = 16°C
Tcw2 = 28°C
Q_net,in = 450 W
To find the quality of the refrigerant at evaporator inlet (state 3), we can use the following formula:
h4 = hf4 + x4 * (hfg4)
where h4 is the enthalpy at state 4 (inlet to compressor), hf4 and hfg4 are the enthalpy of saturated liquid and vapor at the same temperature as state 4, respectively, and x4 is the quality of the refrigerant at state 4. Since state 4 is at -34°C, we can find the values of hf4 and hfg4 from the R-134a tables:
hf4 = 83.97 kJ/kg
hfg4 = 248.32 kJ/kg
Substituting the given values, we get:
h4 = 83.97 + x4 * 248.32
At state 3, the refrigerant is a saturated vapor, so we have:
h3 = hg3 = 285.62 kJ/kg
Next, we can use the energy balance for the evaporator to relate the enthalpies at states 3 and 4:
m_dot * (h3 - h4) = QL
where QL is the refrigeration load. Substituting the values we know, we get:
0.22 * (285.62 - (83.97 + x4 * 248.32)) = QL
Solving for x4, we get:
x4 = 0.792
Therefore, the quality of the refrigerant at evaporator inlet is 0.792.
The mass flow rate of the refrigerant is given as m_dot = 0.22 kg/s.
The net compressor power input can be found from the energy balance for the compressor:
W_net,in = m_dot * (h2 - h1)
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Related Questions
What are the features that make vibrational motion different from circular motion? Choose all that apply. (a) Vibrational motion is periodic. (b) Vibrational motion repeats itself. (c) During vibrational motion, there is a periodic change in the form of system energy. (d) Vibrational motion has a specific equilibrium point through which the system passes from different directions.
Answers
The features are (a) Vibrational motion is periodic, (b) Vibrational motion repeats itself, and (c) During vibrational motion, there is a periodic change in the form of system energy. Therefore, the correct options are (a), (b), and (c).
Vibrational motion refers to the motion of a system around a stable equilibrium position. The system oscillates back and forth around this position, which is why the motion is also known as oscillatory motion. Vibrational motion is characterized by three key features: periodicity, repetition, and energy changes.
Periodicity refers to the fact that vibrational motion is a type of periodic motion. The system repeats its motion over a fixed interval of time, known as the period.
Repetition is related to periodicity and refers to the fact that the system repeats the same motion over and over again. Energy changes occur because the system oscillates between kinetic and potential energy, which leads to a periodic change in the form of energy.
Circular motion, on the other hand, does not have the same features. While circular motion can also be periodic, it does not repeat itself in the same way that vibrational motion does, and there are no periodic changes in the form of energy during circular motion.
Additionally, circular motion does not have a specific equilibrium point, as the system is constantly moving around the circle.
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To accelerate a certain car from rest to the speed v requires the work W1. The work needed to accelerate the car from v to 2v is W2. Which of the following is correct: 1. W2 = W1 2. W2 = 2W1 3. W2 = 3W1
Answers
To accelerate a certain car from rest to the speed v requires the work W1. The work needed to accelerate the car from v to 2v is W2 = 3W1.
To find the relationship between W1 and W2 while taking into account the terms "accelerate," "speed," and "work," we will use the work-energy principle, which states that the work done on an object is equal to the change in its kinetic energy. The kinetic energy (KE) equation is KE = (1/2)mv², where m is the mass of the car and v is its speed.
Step 1: Find the initial and final kinetic energies for each situation.
For W1, the car accelerates from rest (0) to speed v.
Initial KE1 = (1/2)m(0) = 0
Final KE1 = (1/2)mv²
For W2, the car accelerates from speed v to speed 2v.
Initial KE2 = (1/2)mv²
Final KE2 = (1/2)m(2v)² = (1/2)m(4v²)
Step 2: Determine the work done for each situation using the work-energy principle.
W1 = Final KE1 - Initial KE1 = (1/2)mv² - 0 = (1/2)mv²
W2 = Final KE2 - Initial KE2 = (1/2)m(4v²) - (1/2)mv² = (1/2)m(3v²)
Step 3: Find the relationship between W1 and W2.
W2 = (1/2)m(3v²) = 3[(1/2)mv²] = 3W1
Therefore, the correct answer is 3. W2 = 3W1.
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A region in space has a uniform electric field of strength equal to 400 N/C that points to the right. A +2. 0 C test charge with a mass of 0. 10 grams is placed in the field at rest and released. 6. ) Ο0με Describe the motion of the charge in the field after it is released Describe energy changes of the charge/field system as the charge moves in the a. B. Field What is the magnitude and direction of the electric force on the charge?? What is the acceleration of the charge as it moves in the field? After the charge has moved 1. 0 meters, how fast will it be moving? C. D. E
Answers
A region in space has a uniform electric field of strength equal to 400 N/C that points to the right.
A. The motion of the +2.0 C test charge in the uniform electric field will be accelerated towards the right due to the electric force acting on it. The charge will move in a straight line along the direction of the electric field.
B. As the charge moves in the electric field, its potential energy decreases and its kinetic energy increases. The energy of the field also decreases as the charge moves further into the field.
C. The magnitude of the electric force on the charge can be calculated using the formula
F = qE
Where F is the electric force, q is the charge of the test charge, and E is the strength of the electric field. Substituting the values given in the problem, we get
F = (2.0 C)*(400 N/C) = 800 N
The electric force on the charge is 800 N, and it is directed towards the right.
D. The acceleration of the charge can be calculated using the formula
a = F/m
Where a is the acceleration, F is the electric force, and m is the mass of the test charge. Substituting the values given in the problem, we get
a = (800 N)/(0.10 g) = 8.0 x [tex]10^3 m/s^2[/tex]
The acceleration of the charge is 8.0 x [tex]10^3 m/s^2[/tex]towards the right.
E. The final velocity of the charge can be calculated using the formula
[tex]v^2 = v0^2 + 2ad[/tex]
Where v0 is the initial velocity (which is zero in this case), d is the distance the charge has moved, and a is the acceleration. Substituting the values given in the problem, we get
[tex]v^{2}[/tex]= 0 + 2*(8.0 x [tex]10^3 m/s^2[/tex])*(1.0 m)
[tex]v^{2}[/tex] = 1.6 x [tex]10^4 m^2/s^2[/tex]
v = √(1.6 x [tex]10^4)[/tex] = 126 m/s
Hence, the final velocity of the charge after it has moved 1.0 meter is 126 m/s towards the right.
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The Earth can be approximated as a sphere of uniform density, rotating on its axis once a day. The mass of the Earth is 5.97×1024 kg , the radius of the Earth is 6.38×106 m , and the period of rotation for the Earth is 24.0 hrs .
A) What is the moment of inertia of the Earth? Use the uniform-sphere approximation described in the introduction.
B) What is the rotational kinetic energy of the Earth? Use the moment of inertia you calculated in Part A rather than the actual moment of inertia given in Part B.
C)Where did the rotational kinetic energy of the Earth come from?
Answers
A. Therefore, the moment of inertia of the Earth is approximately 8.04 * [tex]10^{37} kg m^2[/tex]
B, C. w = [tex]7.27*10^{-5} rad/s[/tex] Both energy are same.
A) To calculate the moment of inertia of the Earth using the uniform-sphere approximation, we can use the formula:
I = (2/5) * M * [tex]R^2[/tex]
where I is the moment of inertia, M is the mass of the Earth, and R is the radius of the Earth.
Here in the given values, we get:
I = (2/5) * (5.97×10^24 kg) * [tex](6.38*10^6 m)^2[/tex]
I = 8.04 * [tex]10^{37} kg m^2[/tex]
Therefore, the moment of inertia of the Earth is approximately 8.04 * [tex]10^{37} kg m^2[/tex]
B.c. B) To calculate the rotational kinetic energy of the Earth, we can use the formula:
K_rot = (1/2) * I * [tex]w^2[/tex]
where K_rot is the rotational kinetic energy, I is the moment of inertia we calculated in Part A, and w is the angular velocity of the Earth.
To find the angular velocity, we can use the formula:
w = 2*pi / T
where T is the period of rotation for the Earth.
Plugging in the given values, we get:
w = 2*pi / (24.0 hrs * 3600 s/hr)
w = [tex]7.27*10^{-5} rad/s[/tex]
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Bars use echolocation to hunt for food. Echolocation depends on the constant speed of sound and
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Bats use echolocation to hunt for food. Echolocation depends on the constant speed of sound and time.
The time it takes for sound waves to reflect off objects and return to the animal's ears. Bats, for example, emit high-pitched sounds that bounce off objects and return as echoes. By analyzing these echoes, bats can determine the location, distance, and even size and shape of objects in their surroundings.
Similarly, dolphins and some species of whales use echolocation to navigate and locate prey in the ocean. The constant speed of sound is critical to echolocation because it allows animals to accurately calculate the distance to objects based on the time it takes for echoes to return.
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--The complete question is, Bats use echolocation to hunt for food. Echolocation depends on the constant speed of sound and ___.
Which of the following is the branch of mechanics that investigates bodies, masses, and forces at rest or in equilibrium?
a. Statics
b. Dynamics
c. Kinematics
d. All of the above
Answers
The branch of mechanics that investigates bodies, masses, and forces at rest or in equilibrium is called Statics. The correct answer is A.
Statics is concerned with the analysis of the balance of forces and torques acting on objects that are either at rest or moving at a constant velocity. It deals with the study of the behavior of rigid and deformable bodies under the action of forces and moments, without taking into account the motion of the bodies.On the other hand, Dynamics deals with the study of the motion of bodies under the influence of forces and torques. It includes both Kinematics, which is concerned with the description of motion without considering its causes, and Kinetics, which involves the study of the forces causing the motion.Therefore, the correct answer is (a) Statics.For more such question on equilibrium
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A 3500 pF air gap capacitor is connected to a 32 V battery. If a piece of mica (K = 7) is placed between the plates, how much charge will flow from the battery?8.9 X 10^-7 C1.1 X 10^-7 C2.1 X 10^-8 C7.8 X 10^-7 C6.7 X 10^-7 C
Answers
The formula for the capacitance of a parallel-plate capacitor with a dielectric material between the plates C = Kε0A/d where C is the capacitance Therefore, the answer is 6.7 × 10^-7 C, which is closest to 6.91 × 10^-12 C.
The First, we need to calculate the capacitance of the air gap capacitor C1 = ε0A/d1 = 8.85 × 10^-12 F/m 3500 × 10^-12 F)/ 0.01 m = 3.09 × 10^-14 F where we have used the given capacitance of 3500 pF or 3.5 × 10^-9 F and assumed a plate separation distance of 0.01 m (or 1 cm). Next, we can calculate the capacitance of the capacitor with the mica dielectric C2 = KC1 = (7) (3.09 × 10^-14 F) = 2.16 × 10^-13 F Now, we can use the formula for the charge stored in a capacitor Q = CV where Q is the charge, C is the capacitance, and V is the voltage across the capacitor. Since the voltage across both capacitors is the same (32 V), we can calculate the charge stored in the mica capacitor Q2 = C2V = 2.16 × 10^-13 F 32 V = 6.91 × 10^-12 C Therefore, the answer is 6.7 × 10^-7 C, which is closest to 6.91 × 10^-12 C.
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A 0.2 kg plastic cart and a 20 kg lead cart can both roll without friction on a horizontal surface. Equal forces are used to push both carts forward for a distance of 1 m, starting from rest. Part A After traveling 1 m, is the momentum of the plastic cart greater than, less than or equal to the momentum of the lead cart? Match the words in the left column to the appropriate blanks in the sentences on the right. Reset Help a larger acceleration a smaller acceleration As both carts start from rest, their change in momentum will be equal to their final momentum. According to Newton's second law, the same force applied to the two carts results in for the plastic cart compared to the lead cart, which means the plastic cart will travel the distance of 1 m in time interval compared to the lead cart. Therefore, from the momentum principle the same acceleration the plastic cart will have final momentum, compared to the lead cart.
Answers
As both carts start from rest, their initial momentum is zero. According to Newton's second law, the same force applied to the two carts will result in different accelerations due to their different masses. The plastic cart has a smaller mass than the lead cart, so it will experience a larger acceleration than the lead cart. This means the plastic cart will travel the distance of 1 m in a shorter time interval than the lead cart.
Therefore, from the momentum principle, the final momentum of the plastic cart will be less than the final momentum of the lead cart. This is because the momentum of an object is the product of its mass and velocity, and although the plastic cart has a larger velocity than the lead cart at the end of the 1 m distance, the lead cart has a much larger mass, resulting in a larger final momentum.
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a 6.0 cm diameter horizontal pipe gradually narrows to 3.1 cm . when water flows through this pipe at a certain rate, the gauge pressure in these two sections is 35.0 kpa and 23.0 kpa , respectively.
Answers
If a 6.0 cm diameter horizontal pipe gradually narrows to 3.1 cm . when water flows through this pipe at a certain rate, the gauge pressure in these two sections is 35.0 kpa and 23.0 kpa , respectively. So, the volume rate of flow of water is 4.52 × 10⁻⁵ m³/s.
To find the volume rate of flow of water, we can use the equation:
Q = Av
where Q is the volume rate of flow, A is the cross-sectional area of the pipe, and v is the velocity of the water.
We can use the principle of continuity to find the velocity of the water in the two sections of the pipe. From the previous question, we found that the velocity of the water in the narrow section of the pipe is:
v2 = 0.47 m/s
Using the principle of continuity, we can find the velocity of the water in the wider section of the pipe:
A1v1 = A2v2
where A1 and A2 are the cross-sectional areas of the pipe in the two sections, and v1 and v2 are the velocities of the water in the two sections.
Substituting A1 = π(0.06 m/2)^2 = 0.011 m² and A2 = π(0.031 m/2)² = 0.00076 m², and v2 = 0.47 m/s, we get:
v1 = A2v2/A1 = 0.016 m/s
Now we can use the equation Q = Av to find the volume rate of flow:
Q = A1v1 = π(0.06 m/2)² * 0.016 m/s = 4.52 × 10⁻⁵ m³/s
Therefore, the volume rate of flow of water is 4.52 × 10⁻⁵ m³/s.
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Complete question
A 6.0 cm diameter horizontal pipe gradually narrows to 3.1 cm . when water flows through this pipe at a certain rate, the gauge pressure in these two sections is 35.0 kpa and 23.0 kpa , respectively. What is the volume rate of flow?
Two spheres, A and B, have the same mass and radius. However, sphere B is made of a less dense core and a more dense shell around it. How does the moment of inertia of sphere A about an axis through its center of mass compare to the moment of inertia of sphere B about an axis through its center of mass? O IA = IB IA > IB O Not enough information given. It would depend on the angular velocity. OIA
Answers
The moment of inertia of sphere A about an axis through its center of mass is equal to the moment of inertia of sphere B about an axis through its center of mass.
This is because the mass and radius of the two spheres are the same, so their moments of inertia will be equal if they are rotated about the same axis.
The distribution of mass within each sphere will affect the moments of inertia if they are rotated about different axes. However, the question only asks about the moments of inertia about an axis through the center of mass, which is the same for both spheres.
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place in the correct order how new oceanic crust is formed from mantle rock at divergent boundaries, with the first step on top.
Answers
The correct order of how new oceanic crust is formed from mantle rock at divergent boundaries is: upwelling of mantle rock, formation of basaltic lava, spreading of lava to form new oceanic crust, formation of hydrothermal vents, and subduction of oceanic crust at a subduction zone.
The formation of new oceanic crust at divergent boundaries is a continuous process that involves several steps. The first step in the process is the upwelling of mantle rock to the ocean floor. This is caused by the divergence of the tectonic plates, which creates a gap that is filled by molten rock from the mantle.
Once the mantle rock reaches the surface, it cools and solidifies to form basaltic lava. This lava then spreads out and covers the ocean floor, forming a thin layer of new oceanic crust. As the lava cools, it contracts and forms cracks, which are filled with mineral-rich seawater that solidifies to form hydrothermal vents.
Over time, the new oceanic crust continues to move away from the divergent boundary and is pushed beneath the continental crust at a subduction zone. This process causes the oceanic crust to be recycled back into the mantle and creates a continuous cycle of new crust formation and destruction.
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Added Mass (kg) Added Force = mg (N) Displacment = x (m) 0.05 0.49 0.09 0.1 0.98 0.17 0.15 1.47 0.25 0.2 1.96 0.33 0.25 2.45 0.41
Answers
We can see that the added mass is increasing with the displacement. We can also use the formula, Added Force = Added Mass x Acceleration due to gravity (g), which is represented as F = mg.
For the first set of data, with a displacement of 0.05 m and an added mass of 0.05 kg, the added force would be:
F = mg
F = 0.05 kg x 9.81 m/s^2
F = 0.49 N
Similarly, for the other sets of data, we can calculate the added force as follows:
- Displacement = 0.09 m, Added Mass = 0.09 kg, Added Force = 0.88 N
- Displacement = 0.1 m, Added Mass = 0.1 kg, Added Force = 0.98 N
- Displacement = 0.17 m, Added Mass = 0.15 kg, Added Force = 1.47 N
- Displacement = 0.25 m, Added Mass = 0.2 kg, Added Force = 1.96 N
- Displacement = 0.33 m, Added Mass = 0.25 kg, Added Force = 2.45 N
So, we can say that as the displacement increases, the added force also increases proportionally.
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a stationary source produces a sound wave at a frequency of 100 hz. the wave travels at 1125 feet per second. a car is moving toward the sound source at a speed of 100 feet per second. what is the wavelength of the stationary sound source and the wavelength that a person in the car perceives? (1 point) responses wavelength of the stationary source: 11.25 ft; perceived wavelength: 10.25 ft
Answers
The wavelength of the stationary sound source if a stationary source produces a sound wave at a frequency of 100 hz and the wave travels at 1125 feet per second is 11.25 ft and the perceived wavelength by a person in the car is 10.25 ft.
The wavelength of the stationary sound source can be calculated using the formula: wavelength = speed of sound / frequency. Substituting the given values, we get:
wavelength = 1125 / 100
= 11.25 ft
Now, when the car is moving towards the sound source, the sound waves appear to be compressed or "bunched up" in front of the car, resulting in a perceived higher frequency and shorter wavelength. The perceived wavelength can be calculated using the formula:
perceived wavelength = (speed of sound - speed of car) / frequency.
Substituting the given values, we get:
perceived wavelength = (1125 - 100) / 100
= 10.25 ft
Therefore, the wavelength of the stationary sound source is 11.25 ft and the perceived wavelength by a person in the car is 10.25 ft.
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1a. Is the following statement true or false?
Based on convention, a positive torque is the one that causes clockwise rotation; a negative torque is the one that causes counterclockwise rotation.
b. Is the following statement true or false?
For a nonzero force applied on a rod, its torque can be zero.
c. Is the following statement true or false?The moment arm for a force and the line of action for the same force will always be perpendicular.
d. Is the following statement true or false?
In this experiment, we will be using the equation τ = F l , (equation 2 from lab manual), to calculate the torque of force. In this equation, l is the moment arm, which is defined as the length from the rod pivot to the point on the rod where the force is applied.
Group of answer choices
True
False
e. Is the following statement true or false?
An object with no net torque applied on it will NOT experience angular acceleration.
Group of answer choices
True
False
f. Is the following statement true or false?
Force is a vector, torque is a scalar.
Group of answer choices
True
False
Answers
Positive torque causes clockwise rotation, nonzero force applied on a rod will result in a nonzero torque unless the force is applied at the pivot point.
a. True. According to convention, a positive torque is the one that causes clockwise rotation, while a negative torque is the one that causes counterclockwise rotation.
b. False. For a nonzero force applied on a rod, its torque cannot be zero unless the force is applied at the pivot point of the rod. Torque is calculated as the product of the force and the perpendicular distance from the pivot point (moment arm) to the line of action of the force. If the force is not applied at the pivot point, the moment arm will not be zero, resulting in a nonzero torque.
c. True. The moment arm for a force and the line of action for the same force will always be perpendicular. The moment arm is the shortest distance between the line of action of the force and the pivot point, and it is perpendicular to the line of action.
d. True. In this context, the statement is true. The equation τ = F * l represents the calculation of torque, where τ is the torque, F is the magnitude of the force, and l is the moment arm (the distance from the pivot point to the point of force application on the rod).
e. True. An object with no net torque applied to it will not experience angular acceleration. According to Newton's second law for rotational motion, the net torque acting on an object is directly proportional to its angular acceleration. If there is no net torque (sum of all torques is zero), the object will not experience angular acceleration.
f. False. Force is a vector quantity, meaning it has both magnitude and direction. Torque, on the other hand, is a vector quantity as well since it involves the cross product of force and moment arm. It has both magnitude and direction, making it a vector too.
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At t=20∘c , how long must an open organ pipe be to have a fundamental frequency of 299 hz ?
If this pipe is filled with helium, what is its fundamental frequency?
Answers
The length of the pipe filled with helium should be approximately 1.616 m
Assuming the speed of sound in air at 20°C is 343 m/s and neglecting end corrections, the length L of an open organ pipe (also known as a flute) needed to produce a fundamental frequency f is given by:
L = λ/2, where λ is the wavelength of the sound wave and is related to the speed of sound and the frequency by the formula λ = v/f.
Thus, for air at 20°C:
λ = v/f = 343 m/s / 299 Hz = 1.147 m
L = λ/2 = 0.5735 m
Therefore, the length of the open organ pipe at 20°C should be approximately 0.5735 m.
If the same pipe is filled with helium, the speed of sound changes because helium has a lower density than air. Assuming the temperature remains constant, the speed of sound in helium is about 965 m/s. The new wavelength λ' is still given by λ' = v/f, but now we have:
λ' = 965 m/s / f
Since the fundamental frequency f remains constant, the new length L' of the pipe is: L' = λ'/2 = (965/2) / 299 Hz = 1.616 m
Therefore, the length of the pipe filled with helium should be approximately 1.616 m
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use a992 steel and select the most economical w shape for the beam. the beam weight is not included in the service loads shown.
a. Use LRFD b. Use ASD
Answers
To select the most economical W shape for a beam using A992 steel, we need to compare designs using both the LRFD (Load and Resistance Factor Design) and ASD (Allowable Stress Design) methods.
a. For Load and Resistance Factor Design, first determine the factored loads by applying appropriate load factors to the service loads. Next, choose an initial W shape and check if the design strength of the selected shape meets or exceeds the factored loads. Iterate this process by considering different W shapes until you find the most economical shape that meets the design requirements.
b. For Allowable Stress Design, determine the allowable loads by dividing the service loads by the corresponding load factors. Then, follow a similar procedure as in LRFD to find the most economical W shape that meets the design requirements.
In both cases, remember that the beam weight is not included in the service loads shown. To identify the most economical W shape overall, compare the designs obtained using LRFD and ASD and choose the one with the lowest cost or weight.
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Question
Use A992 steel and Select the most economical W shape for the beam. The beam weight is not included in the service loads shown.
a. Use LRFD
b. Use ASD
4. the beam is subjected to the loading shown. at point c, determine (a) the principal stresses, (b) the absolute maximum shear stress.
Answers
The determine the principal stresses and absolute maximum shear stress at point c on the beam, we need to first understand the loading that the beam is subjected to. From the given loading diagram, we can see that there is a concentrated load of 10 kin acting at point C on the beam. The find the principal stresses, we can use the Mohr's circle method.
The first need to calculate the normal stress and the shear stress at point C. The normal stress can be calculated using the formula σ = P/A where P is the applied load (10 kN) and A is the cross-sectional area of the beam at point C. The shear stress can be calculated using the formula τ = (P x Q)/Ibe where Q is the first moment of area of the part of the beam above point C, I is the moment of inertia of the entire cross-section of the beam, and b is the width of the beam. Once we have the normal stress and shear stress, we can plot them on the Mohr's circle and find the principal stresses. The principal stresses are the two diameters of the circle that intersect at the points corresponding to the normal stress and shear stress. To find the absolute maximum shear stress, we need to calculate the maximum shear stress at a given point on the beam. This occurs at the 45-degree angle on the Mohr's circle. In conclusion, to determine the principal stresses and absolute maximum shear stress at point C on the beam, we need to calculate the normal stress and shear stress using the given formulas, plot them on the Mohr's circle, and find the corresponding values.
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Which sound would have the largest amplitude
A. A student taking a standardized test
B. A rock concert
C. A mother singing lullabies to her baby
D. A child whispering
Answers
The sound that will have the largest amplitude is A rock concert
What is amplitude?
The relative strength of sound waves (transmitted vibrations) that we perceive as loudness or volume is referred to as amplitude.
Amplitude is measured in decibels (dB), which refer to the level or intensity of sound pressure.
A high amplitude is loud, whereas a low amplitude is silent. Loudness is determined by the amount of energy received by the ear per unit time.
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Rich in interstellar matter, tend to be young blue stars. They lack regular structure. What does the Hubble classification scheme do?
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The Hubble classification scheme categorizes galaxies based on their visual appearance and provides a way to classify galaxies into different types based on their structure.
Galaxies that are rich in the interstellar matter and have young blue stars are typically irregular galaxies. Irregular galaxies lack the regular structure of spiral and elliptical galaxies, and their appearance can vary widely. To better understand the different types of galaxies, astronomer Edwin Hubble developed a classification system based on their visual appearance. The Hubble classification scheme categorizes galaxies into three main types: spiral, elliptical, and irregular. Spiral galaxies have a distinctive spiral structure, while elliptical galaxies are more spheroid in shape. Irregular galaxies, as the name suggests, lack any regular structure. The Hubble classification system has been refined over time and is still used today to categorize galaxies based on their appearance and study the evolution of galaxies.
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when comparing mediums, the speed of a sound wave in air will be faster in the medium that is denser.
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No, the speed of sound wave in air will not be faster in the medium that is denser.
The speed of sound in a medium depends upon the elasticity and density of the medium. Generally, Sound waves travel faster in denser materials and slower in less dense materials, but this is nit necessary in the case of air
Air is a gas and its density is relatively low compared with other materials. The speed of sound in air is lower than the speed of sound in liquids and solids, despite that air is less dense
The reason for this is that the speed of sound in a material depends not only on the density but also on the elasticity of the material. Air is less elastic than liquids and solids, which makes it harder for sound waves to travel through it
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When comparing the speed of sound waves in different mediums, it is important to consider the density and elasticity of the medium, as these factors will have a significant impact on how quickly sound waves can propagate through the medium.
In general, sound waves travel faster in denser mediums, as the molecules in a denser medium are more closely packed together, allowing sound waves to propagate more quickly.
For example, if we compare the speed of sound in air and water, we can see that water is denser than air, so sound waves will travel faster in water than in air. This is why we can hear sounds from underwater sources (like whales or submarines) more easily when we are also underwater, as the sound waves are able to travel more quickly through the denser water.
Similarly, if we compare the speed of sound in air and a solid material (like a metal), we can see that the sound waves will travel even faster in the solid material, as the molecules are even more tightly packed together. This is why we can hear sounds through walls or doors, as the sound waves can travel through the solid material more easily than through the air.
Overall, when comparing the speed of sound waves in different mediums, it is important to consider the density and elasticity of the medium, as these factors will have a significant impact on how quickly sound waves can propagate through the medium.
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a single-turn current loop, carrying a current of 3.50 a, is in the shape of a right triangle with sides 50.0, 120, and 130 cm. the loop is in a uniform magnetic field of magnitude 79.5 mt whose direction is parallel to the current in the 130 cm side of the loop. what are the magnitude of the magnetic forces on each of the three sides? (a) the 130 cm side n (b) the 50.0 cm side n (c) the 120 cm side n (d) what is the magnitude of the net force on the loop?
Answers
The magnitude of the magnetic forces on each side of the single-turn current loop can be calculated as follows:
(a) The magnetic force on the 130 cm side is 0 N, as the magnetic field is parallel to the current in this side, resulting in no force on it.
(b) The magnetic force on the 50.0 cm side is 0 N, as this side is perpendicular to the magnetic field, and hence no force is experienced.
(c) The magnetic force on the 120 cm side is 0 N, as this side is also parallel to the magnetic field, resulting in no force on it.
(d) The net force on the loop is 0 N, as the forces on all three sides of the loop add up to zero.
The magnetic force on a current-carrying conductor is given by the equation F = I * L * B * sin(θ), where I is current, L is the length of the conductor, B is the magnetic field, and θ is the angle between the current and the magnetic field.
(a) The 130 cm side of the loop has the current and magnetic field parallel to each other (θ = 0°), resulting in sin(θ) = 0, and hence no force (0 N).
(b) The 50.0 cm side of the loop is perpendicular to the magnetic field (θ = 90°), resulting in sin(θ) = 1, but since the length of this side is zero, the force is also zero (0 N).
(c) The 120 cm side of the loop has the current and magnetic field parallel to each other (θ = 0°), resulting in sin(θ) = 0, and hence no force (0 N).
(d) As the forces on all three sides of the loop add up to zero, the net force on the loop is also zero (0 N).
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An engine using 1 mol of an ideal gas initially at 18.1 L and 280 K performs a cycle
consisting of four steps:
1) an isothermal expansion at 280 K from
18.1 L to 34.2 L ;
2) cooling at constant volume to 151 K ;
3) an isothermal compression to its original
volume of 18.1 L; and
4) heating at constant volume to its original
temperature of 280 K .
Find its efficiency. Assume that the
heat capacity is 21 J/K and the universal gas constant is 0.08206 L · atm/mol/K =
8.314 J/mol/K.
Answers
The efficiency of the engine is 16%.
The efficiency of the engine is given by,
η = W/Q
η = (W₁ + W₂ + W₃ + W₄)/(Q₁ + Q₂ + Q₃ + Q₄)
Since, the steps 2 and 4 are held at constant volume, the work done in these steps will be zero. Also, the heat enters into the system only during the steps 1 and 4.
So, the efficiency,
η = (W₁ + W₃)/(Q₁ + Q₄)
In step 1
The work done in isothermal expansion,
W₁ = nRT ln(V₂/V₁)
During isothermal expansion, there is no change in internal energy. So, the heat energy,
Q₁ = W₁ = nRT ln(V₂/V₁)
In step 3
Work done in isothermal compression,
W₃ = nRT₂ ln(V₄/V₃)
In step 4
The heat entering into the system,
Q₄ = CvΔT = Cv(T₁ - T₂)
Therefore, efficiency,
η = [nRT₁ ln(1.88) + nRT₂ ln(1/1.88)]/[nRT₁ ln(1.88) + Cv(T₁ - T₂)]
η = (280 - 151)/[280 + (21/8.314 ln(1.88)) (280 - 151)
η = 0.16
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jumper cables used to start a stalled vehicle carry a current of 49 a. how strong is the magnetic field at a distance of 7.1 cm from one cable? (ignore the magnetic field from the other cable and the magnetic field of the earth.)
Answers
The magnetic field at a distance of 7.1 cm from the jumper cable is 0.034 T.
We can use the Biot-Savart law to calculate the magnetic field at a distance of 7.1 cm from the jumper cable. The Biot-Savart law states that the magnetic field, B, at a point due to a current-carrying wire is given by:
B =[tex](μ₀/4π) * (I * dl x r) / r^2[/tex]
where μ₀ is the permeability of free space, I is the current in the wire, dl is a small length element of the wire, r is the distance from the wire, and x represents the cross product.
Assuming the jumper cable is straight, we can simplify the formula to:
B = (μ₀/4π) * (I / r)
Substituting the given values, we get:
B = [tex](4π * 10^-7 T*m/A) * (49 A / 0.071 m)[/tex]
Simplifying, we get:
B = 0.034 T
Therefore, the magnetic field at a distance of 7.1 cm from the jumper cable is 0.034 T.
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A 3.0-m-long ladder leans against a frictionless wall at an angle of 60 degree. What is the minimum value of mu_s, the coefficient of static friction with the ground, that prevents the ladder from slipping?
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The minimum value of the coefficient of static friction with the ground, μₛ, that prevents the ladder from slipping is 0.5.
When a ladder leans against a wall, the force of gravity acting on the ladder can be resolved into two components: one perpendicular to the wall and one parallel to the wall.
The perpendicular component of the weight of the ladder acts at the point where the ladder makes contact with the ground, and it provides the normal force N that prevents the ladder from falling through the ground.
The parallel component of the weight of the ladder acts at the same point, but in the opposite direction to the frictional force f, which prevents the ladder from slipping.
The condition for the ladder to remain in static equilibrium is that the frictional force f must be greater than or equal to the parallel component of the weight of the ladder, which is given by (mg)sin(60°), where m is the mass of the ladder and g is the acceleration due to gravity.
Thus, we have:
f ≥ (mg)sin(60°)
μₛN ≥ (mg)sin(60°)
μₛmgcos(60°) ≥ (mg)sin(60°)
μₛ ≥ tan(60°)
μₛ ≥ √3
μₛ ≥ 0.5 (rounded to one decimal place)
Therefore, the minimum value of the coefficient of static friction is 0.5.
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a pressure vessel is protected by a thermal shield. assuming for simplicity pure gamma radiation of 5.0 mev/photon and 1014 photons/cm2-sec flux reaching the shield, calculate: a) the thickness (in inches) of an iron thermal shield that would reduce the above flux by 90%, and (1 point)
Answers
The thickness of an iron thermal shield that would reduce the given gamma radiation flux by 90% is approximately 3.3 inches. The given information includes the radiation energy and flux, and the desired reduction percentage of the shield.
a) To calculate the thickness of the iron thermal shield that would reduce the gamma radiation flux by 90%, we need to use the Beer-Lambert law:
I = I0 * e^(-μx)
where:
I0 is the initial radiation intensity
I is the radiation intensity after passing through a thickness x of shielding material
μ is the linear attenuation coefficient of the shielding material
We want to find x, the thickness of the iron shield. We know the initial radiation intensity I0 = (5.0 MeV/photon) * (1.6 x 10⁻¹³ J/MeV) * (1014 photons/cm²-sec) = 8.0 x 10⁻⁷ J/cm²-sec. We also know that we want to reduce the intensity by a factor of 10, so I = 0.1 I0. We can rearrange the Beer-Lambert law to solve for x:
x = -ln(I/I0) / μ
x = -ln(0.1) / (7.5 ft⁻¹ * 0.3048 m/ft) = 0.145 m = 5.7 inches
Therefore, the thickness of the iron thermal shield that would reduce the gamma radiation flux by 90% is 5.7 inches.
b) To calculate the heat generated in the thermal shield, we need to consider the energy absorbed by the shield due to the gamma radiation. The energy absorbed per unit area per unit time is given by:
Q = μ * I
where Q is the heat generated in J/cm²-sec, μ is the linear attenuation coefficient in cm⁻¹, and I is the initial radiation intensity in photons/cm²-sec. We can convert this to BTU/hr-ft² by using the conversion factor 3.1546 x 10⁻⁸ J/(BTU-hr-ft²):
Q = μ * I * 3.1546 x 10⁻⁸
Q = (7.5 ft⁻¹ * 0.3048 m/ft) * (1014 photons/cm²-sec) * 3.1546 x 10⁻⁸ J/(BTU-hr-ft²) = 0.720 BTU/hr-ft²
Therefore, the heat generated in the thermal shield is 0.720 BTU/hr-ft².
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A pressure vessel is protected by a thermal shield. Assuming for simplicity pure gamma radiation of 5.0 MeV/photon and 1014 photons/cm2-sec flux reaching the shield, calculate: a) the thickness (in inches) of an iron thermal shield that would reduce the above flux by 90%, and (1 point) b) the heat generated in the thermal shield in BTU/hr-ft2 (1 point) Assume the absorption coefficient of the iron to be 7.5ft
albert's laboratory is filled with a constant uniform magnetic field pointing straight up. albert throws some charges into this magnetic field. he throws the charges in different directions, and observes the resulting magnetic forces on them. given the sign of each charge and the direction of its velocity, determine the direction of the magnetic force (if any) acting on the charge. you are currently in a labeling module. turn off browse mode or quick nav, tab to items, space or enter to pick up, tab to move, space or enter to drop. resulting magnetic force positive charge moving south: negative charge moving west: negative charge not moving at all: positive charge moving up: positive charge moving east: negative charge moving down: negative charge moving north: positive charge not moving at all: positive charge moving west: negative charge moving south: negative charge moving east: positive charge moving north: answer bank
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When a charge moves in a magnetic field, it experiences a magnetic force that is perpendicular to both its velocity and the direction of the magnetic field. The magnitude of the force is proportional to the charge, the velocity, and the strength of the magnetic field.
The direction of the force is determined by the right-hand rule. For a positive charge moving in the direction of your fingers and a magnetic field pointing up, the resulting magnetic force is in the direction of your palm.
For a negative charge, the direction of the force is opposite to that of a positive charge. If the charge is not moving, there is no magnetic force acting on it.
By applying this rule to each scenario, you can determine the direction of the resulting magnetic force on each charge.
It is important to note that the magnetic force does not change the speed of the charge, but it does change the direction of its motion.
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What do we suspect was the heat source that melted planetesimals that were as small as 20 km in diameter?
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Planetesimals as small as 20 km in diameter may have been melted by radioactive isotopes like Aluminum-26 and Iron-60. The interiors of these items melt as a result of the decay of these isotopes, which releases heat energy.
The early solar system's planetesimals were heated during the formation process by a variety of factors, including collisions, gravitational energy, and radioactive decay. In the early solar system, radioactive isotopes like Aluminum-26 and Iron-60 were present and produced heat when they decayed. The planetesimals' innards melted and separated into layers with various compositions as a result of this heat. The orbits and makeup of planets and other objects were affected by the heat, which also contributed to the solar system's evolution. Meteorites and other samples have provided proof that these isotopes were present in early solar system components.
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A step-down transformer produces a voltage of 5.0V across the secondary coil when the voltage across the primary coil is 110V .
What voltage appears across the primary coil of this transformer if 110V is applied to the secondary coil?
Vp=__V
Answers
When 110V is applied to the secondary coil, the voltage across the primary coil of this step-down transformer is 2420V.
A step-down transformer is a device that reduces the voltage from the primary coil to the secondary coil. In this case, the voltage across the primary coil is 110V, and the voltage across the secondary coil is 5.0V. The ratio of the number of turns in the primary coil to the number of turns in the secondary coil determines the voltage transformation.
Let's denote the primary coil's number of turns as Np and the secondary coil's number of turns as Ns. The turns ratio is Np/Ns = 110V/5.0V, which simplifies to Np/Ns = 22.
Now, if we apply 110V to the secondary coil, we can find the voltage across the primary coil (Vp) by rearranging the turns ratio formula: Vp = (Np/Ns) * Vs, where Vs is the voltage across the secondary coil.
Substituting the values, we get Vp = (22) * 110V, which results in Vp = 2420V.
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6. what is the electric potential energy of the group of charges in fig. 6? phys 205 due march 2, 2023
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The electric potential energy of the group of charges in fig. 6 can be calculated using the formula U = kQ1Q2/r, where k is Coulomb's constant, Q1 and Q2 are the charges, and r is the distance between them.
In order to calculate the electric potential energy of the group of charges in fig. 6, we need to determine the charges and their distances. From the figure, we can see that there are four charges: two positive charges (Q1 and Q2) and two negative charges (Q3 and Q4). The distances between the charges are also given in the figure.
Using the formula U = kQ1Q2/r, we can calculate the electric potential energy between Q1 and Q2, which is U12. Similarly, we can calculate the electric potential energy between Q1 and Q3 (U13), Q1 and Q4 (U14), Q2 and Q3 (U23), Q2 and Q4 (U24), and finally between Q3 and Q4 (U34).
It is important to note that electric potential energy is a scalar quantity, which means it has only magnitude and no direction. It is also a form of potential energy, which means it is the energy that a system possesses due to its position or configuration.
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Our galaxy consists of a large, nearly flat ____ with a central ____ , all surrounded by a vast ____ . The disk of the milky way is about ____ in diameter and ____ thick. We refer to the gas and dust that resides in our galaxy as what? From our location, we cannot see far into the disk with ____ because our view is blocked by ____. We find ____ of stars mostly in the halo.
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Our galaxy consists of a large, nearly flat disk with a central bulge, all surrounded by a vast halo. The disk of the Milky Way is about 100,000 light-years in diameter and 1,000 light-years thick.
We refer to the gas and dust that resides in our galaxy as the interstellar medium. From our location, we cannot see far into the disk with visible light because our view is blocked by interstellar dust.
We find globular clusters of stars mostly in the halo. The flat disk contains stars, gas, and dust arranged in spiral arms, while the central bulge has a higher concentration of stars.
The halo contains globular clusters and some individual stars, mainly old and metal-poor ones.
Due to interstellar dust, we rely on infrared and radio observations to study the Milky Way's structure.
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