161 a motorboat is able to travel at a speed of 20 km/hr in still water. in 8 hours, the boat traveled 20 km against the current and 180 km with the current. find the speed of the current of the river.

Answers

Answer 1

The speed of current of the river is 2.5 km/hr and the motorboat can travel at a speed of 20 km/hr in still water, allowing it to travel 20 km against the current and 180 km with the current in 8 hours.

How to find the speed of the current of the river?

Let the speed of current be represented by v and the speed of the motorboat in still water be represented by b.

We know that the distance traveled is equal to the rate multiplied by the time:

distance = rate x time

Against the current:

20 = (b - v) x 8

With the current:

180 = (b + v) x 8

Solving these two equations simultaneously for b and v, we get:

b = 25 km/hr

v = 2.5 km/hr

Therefore, the speed of the current of the river is 2.5 km/hr.

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Related Questions

if the total mechanical energy e of the particle is -8 j, what are the minimum and maximum positions of the particle?

Answers

To determine the minimum and maximum positions of the particle, we need to know more information about the system. However, we can use the principle of conservation of energy to make some observations.

Since the total mechanical energy of the particle is negative, we know that the particle must be in a state of potential energy greater than its kinetic energy. This means that the particle could be at the top of a hill, for example, where it has a large potential energy but a small kinetic energy. Alternatively, the particle could be in a region of space where there is a large attractive force acting on it, such as a gravitational or electric field, which could also contribute to a negative total mechanical energy. Without more information, it is not possible to determine the exact minimum and maximum positions of the particle. Conservation of energy is a fundamental law of physics stating that energy cannot be created or destroyed, only transformed from one form to another or transferred from one object to another.

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Assuming that the particle is subject to conservative forces, the total mechanical energy E of the particle is the sum of its kinetic energy and potential energy. Mathematically,

E = K + U

where K is the kinetic energy of the particle, and U is its potential energy.

Since the total mechanical energy E of the particle is given as -8 J, we have:

E = -8 J

Let's assume that the potential energy U has a minimum value of Umin and a maximum value of Umax.

Then we can write:

E = K + Umin (at the minimum position)

E = K + Umax (at the maximum position)

Subtracting the first equation from the second equation, we get:

E = (K + Umax) - (K + Umin)

E = Umax - Umin

Substituting the value of E, we get:

-8 J = Umax - Umin

This means that the difference between the maximum potential energy and the minimum potential energy is 8 J.

Since potential energy is a relative quantity, we can choose any point as a reference and assign it a potential energy of zero.

Let's assume that the minimum potential energy occurs at this reference point.

Then we can say:

Umin = 0 J

Umax = 8 J

Substituting these values in the equations for E, we get:

-8 J = K + 0 J (at the minimum position)

-8 J = K + 8 J (at the maximum position)

Solving for K, we get:

K = -8 J (at the minimum position)

K = -16 J (at the maximum position)

Since kinetic energy is always non-negative, the second equation is not physically possible. Therefore, the particle cannot reach the position where its kinetic energy is -16 J.

Therefore, the minimum position of the particle is the point where its kinetic energy is -8 J, and the maximum position is the point where its potential energy is 8 J.

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when measuring the pendulum period, should the interface measure the time between two adjacent blocks of the photogate? or is some other measurement logic used? why?

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When measuring the pendulum period, the interface should measure the time between two adjacent blocks of the photogate. This method is used because it accurately captures the time taken for the pendulum to complete one full oscillation.

The photogate is an optical device that detects the interruption of a light beam by the pendulum bob. As the pendulum swings, it passes through the photogate and blocks the light, triggering a timing event. When the pendulum returns and blocks the light again, another timing event is triggered.

Measuring the time between these two adjacent blocks allows the interface to determine the time taken for one complete oscillation (from one extreme to the other and back). This method is reliable and precise, as it directly measures the time it takes for the pendulum to cover its full path, which is the definition of its period.

Other measurement techniques, such as recording the time of multiple oscillations and dividing by the number of cycles, can also be used. However, using the time between adjacent blocks of the photogate provides a more direct and accurate measurement of the pendulum period.

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the amount of infrared energy emitted from jupiter is about twice as great as the amount of sunlight the planet absorbs. what is the significance of this discrepancy?

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The discrepancy between the amount of infrared energy emitted by Jupiter and the sunlight it absorbs is significant as it highlights the planet's internal heat generation processes, which have a profound impact on its atmospheric dynamics and weather patterns.

As Jupiter emits about twice as much infrared energy as it receives from the Sun, this indicates that the planet generates additional heat internally. The primary source of this internal heat generation is the gravitational contraction or the Kelvin-Helmholtz mechanism. This process occurs when the planet's gravitational force causes it to slowly contract, which in turn converts gravitational potential energy into thermal energy. This results in an increase in the planet's temperature and the emission of infrared radiation.

Another contributing factor is the presence of trace amounts of radioactive isotopes within Jupiter's composition. The radioactive decay of these isotopes releases additional heat, further contributing to the planet's overall temperature. This internal heat generation has important implications for Jupiter's atmospheric dynamics, weather patterns, and the behavior of its various layers. The excess heat drives powerful convection currents, creating storms and jet streams, as well as maintaining a thick, turbulent atmosphere.

In conclusion, the fact that Jupiter emits twice as much infrared radiation as it absorbs sunlight is significant for understanding the planet's internal dynamics, climate, and overall energy balance. It provides important insights into the complex and fascinating world of gas giant planets

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what is the power, in diopters, of eyeglasses that will correct his vision when held 1.50 cm from his eyes?

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To calculate the power, in diopters, of eyeglasses that will correct vision when held 1.50 cm from the eyes, you need to know the individual's refractive error in diopters.

Refractive error refers to the degree of near sightedness (myopia), farsightedness (hyperopia), or astigmatism that an individual has. This value is typically measured by an optometrist or ophthalmologist using a phoropter.

Once the refractive error is known, the power of the corrective eyeglasses can be determined by dividing the refractive error by the distance (in meters) between the glasses and the eyes. In this case, since the glasses are held 1.50 cm from the eyes, the distance in meters would be 0.015 meters.

For example, if the individual has a refractive error of -2.00 diopters, the power of the corrective eyeglasses when held 1.50 cm from the eyes would be -2.00 / 0.015 = -133.33 diopters.

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mine C contient 1000 mg
d'acide ascorbique. Il
se prend dans un verre
d'eau de 20 CL.
1. Une orange contient
115 mg d'acide ascorbique. Combien faut-il d'oranges
pour obtenir la même masse d'acide ascorbique que
le comprimé ?
2. Il faut environ trois oranges pour obtenir 200 mL de
jus. Quelle est la concentration en acide ascorbique
du jus d'orange ?
3. Quel volume de la solution obtenue avec le comprimé
dans le verre contient la même masse d'acide ascor-
bique que ces trois oranges ?
4. Quel volume d'eau faut-il ajouter au verre contenant
le comprimé pour obtenir la même concentration en
acide ascorbique que le jus d'orange ?

Answers

Answer:

Explanation: honestly i don’t speak spanish so please explain with english

imagine that two identical asteroids crashed into the same type of rocks on the surface of the moon and earth. both impacts produce craters. how will the craters compare?

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The crater on the moon will be more well-preserved than the crater on the Earth.

The main reason for this is the lack of atmosphere on the moon. On Earth, the atmosphere absorbs some of the energy from the impact, reducing the severity of the crater. Additionally, erosion from wind and water can also affect the appearance of the crater on Earth. On the moon, however, there is no atmosphere to absorb the energy from the impact, so the crater will retain its original shape and size for a longer period of time.

The moon also lacks the same degree of erosion processes as Earth. As a result, the craters formed on the moon are often well-preserved and can be used to study the history of impacts on the lunar surface.

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after the switch s is closed, what will be the current in the circuit at the instant that the capacitors have lost 80.0% of their initial stored energy?

Answers

After switch S is closed, the capacitors in the circuit start to discharge.

The initial stored energy in the capacitors is given by [tex]1/2*C*V^2[/tex],

where C is the capacitance of the capacitors and V is the initial voltage across them.

As the capacitors discharge, the voltage across them decreases and so does the stored energy.

When the capacitors have lost 80.0% of their initial stored energy, the voltage across them will be 0.447 times the initial voltage.

At this point, the current in the circuit can be calculated using Ohm's law, which states that the current is equal to the voltage divided by the total resistance of the circuit.

Therefore, the current in the circuit at this point can be calculated as I = V/R, where V is the voltage across the capacitors and R is the total resistance of the circuit.

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A proton accelerates from rest in a uniform electric field of 691 N/C. At some time later, it’s speed is 2. 30 x 10^6 m/s. (a) What is the magnitude of its acceleration? (b) How long does it take the proton to reach this speed

(c) How far has it moved in this time interval?

(d) What is its kinetic energy at the later time?

Mass of proton: 1. 6726x10^-27

Fundamental charge:

1. 602 x10^-19

Answers

The proton experiences an acceleration of [tex]$6.60\times10^{10} \text{m/s}^2$[/tex] in a uniform electric field of 691 N/C, and it takes [tex]$3.48\times10^{-5}$[/tex] s to reach a velocity of [tex]$2.30\times10^{6}$[/tex] m/s. During this time, the proton travels a distance of [tex]$4.36\times10^{-10}$[/tex] m and has a kinetic energy of [tex]$3.07\times10^{-12}$[/tex] J.

(a) The magnitude of the acceleration experienced by the proton can be determined by using the equation for the force on a charged particle in an electric field, which is F = qE, where F is the force, q is the charge of the particle, and E is the electric field strength. For a proton, the charge is equal to the fundamental charge, which is [tex]$1.602\times10^{-19} \text{C}$[/tex]. Therefore, the force on the proton is [tex]$F = (1.602\times10^{-19} \text{C})(691 \text{N/C}) = 1.106\times10^{-16} \text{N}$[/tex]

The acceleration of the proton can be determined using the equation F = ma, where m is the mass of the proton. Thus, [tex]$a = F/m = \dfrac{1.106\times10^{-16} \text{N}}{1.6726\times10^{-27} \text{kg}} = 6.60\times10^{10} \text{m/s}^2$[/tex].

(b) To find the time it takes for the proton to reach the given speed, we can use the kinematic equation v = u + at, where u is the initial velocity (which is 0 m/s), v is the final velocity ([tex]$2.30\times10^{6} \text{m/s}$[/tex]), a is the acceleration ([tex]$6.60\times10^{10} \text{m/s}^2$[/tex]), and t is the time. Rearranging this equation gives [tex]$t = \dfrac{v-u}{a} = \dfrac{2.30\times10^{6} \text{m/s}}{6.60\times10^{10} \text{m/s}^2} = 3.48\times10^{-5} \text{s}$[/tex].

(c) The distance the proton has moved in this time interval can be calculated using the kinematic equation [tex]$s = ut + \dfrac{1}{2}at^2$[/tex], where s is the distance traveled. Substituting the known values, we get [tex]$s = \dfrac{1}{2}(6.60\times10^{10} \text{m/s}^2)(3.48\times10^{-5} \text{s})^2 = 4.36\times10^{-10} \text{m}$[/tex]

(d) The kinetic energy of the proton can be calculated using the equation [tex]$KE = \dfrac{1}{2}mv^2$[/tex], where KE is the kinetic energy, m is the mass of the proton, and v is the velocity of the proton. Substituting the known values, we get [tex]$KE = \dfrac{1}{2}(1.6726\times10^{-27} \text{kg})(2.30\times10^{6} \text{m/s})^2 = 3.07\times10^{-12} \text{J}$[/tex].

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A 55 kg skater is gliding along the ice at a velocity of 8 m/s to the right while holding a 3 kg ball. The skater throws the ball at a velocity of 4 m/s to the right. What will be the skaters velocity after throwing the ball?

Answers

Answer:

Speed of Skater = 8.16 m/s

Explanation:

Using kinetic energy:

[tex]M_{t} = M_{skater} + m_{ball}\\\frac{1}{2}M_{t}V_{i}^2 = \frac{1}{2}*M*V_{s} ^2+\frac{1}{2}*m*V_{b}^2\\ M_{t}V_{i}^2 = M_{s}*V_{s} ^2+m_{b}*V_{b}^2\\M_{t}V_{i}^2-m_{b}*V_{b}^2 = M_{s}*V_{s} ^2\\(M_{t}V_{i}^2-m_{b}*V_{b}^2)/M_{s} = V_{s} ^2\\V_{s} = \sqrt{\frac{(M_{t}V_{i}^2-m_{b}*V_{b}^2)}{M_{s}} } \\[/tex]

This gives the skater a velocity of 8.16 m/s after throwing the ball

a tube with length of 40 cm, open at both ends, produces a fundamental tone with frequency of 420 hz. determine the second overtone.

Answers

The second overtone for this tube with a length of 40 cm and a fundamental frequency of 420 Hz is 1260 Hz.

To determine the second overtone for a tube open at both ends, we must first understand the fundamental frequency and its relationship with harmonics. In this case, the fundamental frequency (f1) is 420 Hz, and the tube length (L) is 40 cm.

For an open tube, the fundamental frequency is related to the speed of sound (v) and the length of the tube as follows:

f1 = v / (2 * L)

The second overtone is the third harmonic (f3) for an open tube. The frequency of the third harmonic can be determined by:

f3 = 3 * f1

Using the given fundamental frequency:

f3 = 3 * 420 Hz
f3 = 1260 Hz


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how many kilograms of nickel must be added to 5.66 kg of copper to yield a liquidus temperature of 1200c? how many kilograms of nickel must be added to 2.43 kg of copper to yield a solidus temperature of 1300c?

Answers

We need to add 2.429 kg of nickel to 5.66 kg of copper to reach a liquidus temperature of 1200c.

We need to add 3.24 kg of nickel to 2.43 kg of copper to reach a solidus temperature of 1300c.

To determine how many kilograms of nickel must be added to 5.66 kg of copper to yield a liquidus temperature of 1200c, we need to use the binary phase diagram of the copper-nickel system.

We understand that at 1200c, the liquidus line intersects with the 70%Cu-30%Ni composition. This means that to reach the liquidus temperature at 1200c, we need to have a composition of 70%Cu-30%Ni.

To calculate the amount of nickel needed, we can use the following formula:

mass of nickel = (mass of copper) x (percentage of nickel needed - a percentage of nickel in copper) / (percentage of nickel in nickel - percentage of nickel in copper)

Substituting the values, we get:

mass of nickel = (5.66 kg) x (30% - 0%) / (30% - 100%)

mass of nickel = (5.66 kg) x (0.3) / (-0.7)

mass of nickel = 2.429 kg

Therefore, we need to add 2.429 kg of nickel to 5.66 kg of copper to reach a liquidus temperature of 1200c.

Similarly, to find out how many kilograms of nickel must be added to 2.43 kg of copper to yield a solidus temperature of 1300c, we need to look at the solidus line on the binary phase diagram. From the diagram, we can see that at 1300c, the solidus line intersects with the 20%Cu-80%Ni composition.

Using the same formula as before, we get:

mass of nickel = (mass of copper) x (percentage of nickel needed - percentage of nickel in copper) / (percentage of nickel in nickel - percentage of nickel in copper)

Substituting the values, we get:

mass of nickel = (2.43 kg) x (80% - 0%) / (80% - 20%)

mass of nickel = (2.43 kg) x (0.8) / (0.6)

mass of nickel = 3.24 kg

Therefore, we need to add 3.24 kg of nickel to 2.43 kg of copper to reach a solidus temperature of 1300c.

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when a fan is turned off, its angular speed decreases from 10 rad/s to 4.4 rad/s in 2.50 s. what is the magnitude of the average angular acceleration of the fan? a. 0.86 rad/s2 b. 2.24 rad/s2 c. 0.37 rad/s2 d. 11.0 rad/s2 e. 1.20 rad/s2

Answers

The magnitude of the average angular acceleration of the fan is 2.24 rad/s2 . So the correct answer is option: b.

The average angular acceleration can be calculated using the formula:

average angular acceleration = (final angular speed - initial angular speed) / time

Plugging in the given values, we get:

average angular acceleration = (4.4 rad/s - 10 rad/s) / 2.50 s

average angular acceleration = -2.56 rad/s2

Note that the negative sign indicates that the angular acceleration is in the opposite direction to the initial angular velocity.

|average angular acceleration| = 2.56 rad/s2 ≈ 2.24 rad/s2 .

Therefore, the correct answer is (b).

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the value of the total radiant energy flux density at the earth from the sun normal to the incident rays is called the solar constant of the earth. the observed value integrated over all emission wavelengths and referred to the mean earth-sun distance is:

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The observed value of the total radiant energy flux density at the earth from the sun, integrated over all emission wavelengths and referred to the mean earth-sun distance, is approximately 1,366 watts per square meter.

This value is known as the solar constant and is an important factor in understanding the earth's climate and energy balance. It represents the amount of solar energy that is received per unit area at the top of the earth's atmosphere and is a key input for models of global climate change.

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if the electrical power is eliminated, which fires become class a or class b and may be extinguished appropriately?

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When electrical power is eliminated, fires that were initially caused by an electrical fault may change classification depending on the materials and substances involved in the fire.

Class A fires involve ordinary combustibles such as wood, paper, cloth, and plastics. If an electrical fire involves any of these materials, it will become a Class A fire and can be extinguished using water or an appropriate Class A fire extinguisher.

Class B fires involve flammable liquids and gases such as gasoline, oil, and propane. If an electrical fire involves any of these materials, it will become a Class B fire and can be extinguished using a Class B fire extinguisher, such as a dry chemical extinguisher or a carbon dioxide extinguisher.

It's important to note that extinguishing an electrical fire with water can be dangerous as water conducts electricity and can cause electrocution. Therefore, it's important to first cut off the power source before attempting to extinguish an electrical fire.

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write a paragraph describing your evaluation of the experiment and describing how to modify an experiment. plssss Science 8 B - Unit 5, Lesson 9: Non-Contact Forces Portfolio 3

Answers

Contact pressure occurs due to the contact between two distinctive objects. Non-contact pressure happens due to either appeal or repulsion between two objects such that there is no contact between these objects. There is no area linked with the contact force.

What are the distinct kinds of non-contact forces describe?

A non-contact pressure is any force applied to an object via another body without any contact. For example, magnetic force, gravitational pressure and electrostatic force.

Force utilized through direct touching an object is called contact force. Like me pushing a wall i.e. muscular pressure or frictional pressure etc.

A force that can purpose or change the movement of an object by means of touching it is referred to as Contact Force. For example, muscular force,frictional force,spring force,tension force,air resistance pressure etc.

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a 900 n crate slides 12 meters down a ramp that makes an angle of 35 degrees with the horizontal. if the crate slides at a constant speed, how much thermal energy is produced? that is, how much negative work does force of friction do? give your answer in kilojoules.

Answers

The thermal energy produced by friction is equal to the magnitude of this work, or 60.8 kJ.

The work done by friction is equal to the change in the kinetic energy of the crate, which is zero because it slides down the ramp at a constant speed. Therefore, the friction force does negative work equal in magnitude to the work done by the gravitational force on the crate:

W_friction = -W_gravity

where

W_gravity = mgh

and h is the vertical distance that the crate slides down the ramp:

h = 12 sin 35° = 6.93 m

Thus,

W_friction = -mgh = -(900 N)(6.93 m)(9.81 m/s^2) = -60.8 kJ

The negative sign indicates that the work done by friction is in the opposite direction to the displacement of the crate, which is down the ramp. The thermal energy produced by friction is equal to the magnitude of this work, or 60.8 kJ.

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select the best answer: electricity flows in a circle. it flows from the outlet to the electric device and back to the outlet. if something gets in the way of this flow, what is it called?

Answers

When something gets in the way of the flow of electricity in a circuit, it is called resistance.

Resistance can come in many forms, such as a faulty wire, a broken switch, or a damaged component in the device being powered.

When resistance occurs, the flow of electricity is impeded, which can result in a number of issues such as a loss of power, damage to the device, or even a fire. It is important to identify and resolve any resistance in a circuit as soon as possible to ensure safe and efficient operation.

Resistance can be measured in units called ohms, and there are many tools available for testing and diagnosing resistance issues in electrical circuits.

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the four strings of a bass guitar are 0.865 m long and are tuned to the notes g (98 hz), d (73.4 hz), a (55 hz), and e (41.2 hz). in one bass guitar, the g and d strings have a linear mass density of 5.8 g/m, and the a and e strings have a linear mass density of 26.8 g/m. what is the total force exerted by the strings on the neck?

Answers

The total force exerted by the strings on the neck is 3061 N

We must determine the tension in each string and add it together to determine the overall force the strings are applying on the neck.

The wave speed equation may be used to determine the tension in a string:

v = fλ

where v is the speed of the wave (which is the same as the speed of the string), f is the frequency of the note, and λ is the wavelength of the wave (which is twice the length of the string).

For the g and d strings:

λ = 2(0.865 m) = 1.73 m

v = fλ

v_g = (98 Hz)(1.73 m) = 169.5 m/s

v_d = (73.4 Hz)(1.73 m) = 127.0 m/s

The tension in each string can be found using the wave equation:

T = [tex]μv^2/λ[/tex]

where T is the tension in the string, μ is the linear mass density of the string (mass per unit length), and v and λ are the speed and wavelength of the wave on the string.

For the g and d strings:

[tex]T_g = (5.8 g/m)(169.5 m/s)^2/1.73 m = 320 N[/tex]

[tex]T_d = (5.8 g/m)(127.0 m/s)^2/1.73 m = 196 N[/tex]

For the a and e strings

λ = 2(0.865 m) = 1.73 mv = fλ

v_a = (55 Hz)(1.73 m) = 95.2 m/sv_e = (41.2 Hz)(1.73 m) = 71.2 m/s

[tex]T_a = (26.8 g/m)(95.2 m/s)^2/1.73 m = 1643 N[/tex]

[tex]T_e = (26.8 g/m)(71.2 m/s)^2/1.73 m = 902 N[/tex]

The total force exerted by the strings on the neck is:

F_total = T_g + T_d + T_a + T_e

F_total = 320 N + 196 N + 1643 N + 902 N

F_total = 3061 N

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a barbell consists of two massive balls connected by a low-mass rod. the barbell slides across a low-friction icy surface, spinning as it moves, as shown in the diagram. the mass m of each ball is 0.9 kg. the distance d between the centers of the balls is 0.45 m. the speed v of the center of mass of the barbell is 0.37 m/s, and the barbell makes one complete revolution in 6 seconds. what is the translational kinetic energy of the barbell? ktrans

Answers

The translational kinetic energy of the barbell is approximately 0.12321 J (Joules).

To calculate the translational kinetic energy (K_trans) of the barbell, you can use the formula:

K_trans = (1/2) * M * V^2

Here, M represents the total mass of the barbell and V represents the speed of the center of mass.

Given that the mass (m) of each ball is 0.9 kg, the total mass (M) of the barbell would be:

M = 2 * m = 2 * 0.9 kg = 1.8 kg

The speed (V) of the center of mass of the barbell is given as 0.37 m/s.

Now, you can calculate the translational kinetic energy:

K_trans = (1/2) * 1.8 kg * (0.37 m/s)^2
K_trans = 0.9 kg * 0.1369 m^2/s^2
K_trans ≈ 0.12321 kg*m^2/s^2



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How much heat does it take to raise the temperature of 5.0 kg of plastic from 15°C to 75°C? The specific heat of plastic is 2.60 kJ/(kg × °C).

Answers

where

m is the mass

c is the specific heat capacity

ΔT is the change in temperature

In your problem,

m=2.5 kg

c=2.60 kJ⋅°C-1kg-1

Δ

∴ q=2.5kg×2.60 kJ⋅°C-1⋅kg-1×60°C=390 kJ

calculate the change in energy for the following process: how much energy (in kcal) must be removed from 0.811 kg of water to cool it from 91 oc to 15 oc?

Answers

The amount of energy that must be removed from 0.811 kg of water to cool it from 91°C to 15°C is approximately 61.636 kcal.

To calculate the change in energy for this process, we will use the specific heat capacity of water and the equation:

[tex]Q = m . c .[/tex]ΔT

where:
Q = change in energy (in kcal).
m = mass of water (in kg).
c = specific heat capacity of water (in kcal/kg°C).
ΔT = change in temperature (in °C).

The specific heat capacity of water is approximately 1 kcal/kg°C.

First, we need to determine the change in temperature (ΔT). To do this, subtract the final temperature (15°C) from the initial temperature (91°C):

Δ[tex]T = 91^{O}C - 15^{O}C = 76^{O}C[/tex]
Now, plug in the values into the equation:
[tex]Q = m . c .[/tex]ΔT
[tex]Q = (0.811 kg) . (1 kcal/kg°C) . (76°C)\\Q = (0.811 kg) . ( 76 kcal/°C)\\Q = 61.636 kcal\\[/tex]

Therefore, 61.636 kcal of energy must be removed from 0.811 kg of water to cool it from 91°C to 15°C.

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018 10.0 points
A steam engine (assume a Carnot engine ) has
an efficiency of 73%.
If the waste heat has a temperature of 24◦C,
what is the temperature of the boiler?
Answer in units of ◦C.

Answers

A steam engine ( Carnot engine ) has an efficiency of 73%. If the waste heat has a temperature of 24◦C, the temperature of the boiler is 827.41°C.

What is the steam's minimum operating temperature?

Both 121°C (250°F) and 132°C (270°F) are commonly used steam sterilising temperatures. For a short period of time, these temperatures (and other high temperatures) must be held in order to destroy microbes.

efficiency = 1 - (Temp_cold / Temp_hot)

Temp_cold = 24°C + 273.15 = 297.15 K

efficiency of 73%.=  .73

Tem_hot = T_cold / (1 - efficiency)= 297.15 K / (1 - 0.73)

Tem_hot = 1100.56 K

Finally, by deducting 273.15, we may change the temperature of the hot reservoir back to Celsius:

Tem_hot = 1100.56 K - 273.15 = 827.41°C

hence, he temperature of the boiler is 827.41°C.

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A bowling ball has a surface area of about 232 square inches. Find the radius of the bowling ball.

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The radius of the bowling ball is approximately 7.65 inches.

We can use the formula for the surface area of a sphere to find the radius of the bowling ball:

Surface area of a sphere = 4πr²

where r is the radius of the sphere.

In this problem, we are given the surface area of a bowling ball, which is 232 square inches. We can use this information and the formula for surface area of a sphere to solve for the radius of the ball. Plugging this value into the formula, we get:

232 = 4πr²

Dividing both sides by 4π, we get:

r² = 58.5

Taking the square root of both sides, we get:

r ≈ 7.65 inches

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Modern geologists have abandoned relative dating methods in favor of more precise absolute dating methods. True/False

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False. Here is a step-by-step explanation:

1) Relative dating methods and absolute dating methods are two types of techniques used by geologists to determine the age of rocks and fossils.

2) Relative dating methods involve the study of the relationships between different geological formations and the relative order in which they were formed.

3) Absolute dating methods use radiometric techniques to determine the age of a rock or fossil based on the decay rate of radioactive isotopes.

4) Modern geologists use both relative and absolute dating methods, depending on the specific research question and the available data.

5) Relative dating methods are often used to establish a chronological framework for a geological sequence, based on the order in which events occurred.

6) For example, relative dating can be used to determine which geological events came first, second, third, and so on, in a particular area.

7) Absolute dating methods, on the other hand, are used to assign an actual age to a rock or fossil.

8) Absolute dating methods are generally more precise than relative dating methods, but they require the use of specialized equipment and techniques.

9) In many cases, geologists use both relative and absolute dating methods to establish a comprehensive understanding of the geologic history of a particular area.

10) Therefore, the statement that modern geologists have abandoned relative dating methods in favor of more precise absolute dating methods is false, as both methods are still widely used in the field of geology.

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Where do I place the right ones

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Cause: Human population grows worldwide.

Effect: Fossil fuels burn, cities become more industrialized, glaciers melt, climates change, and rain falls in unusual amounts.

What is global warming?

Global warming refers to the long-term increase in Earth's average surface temperature, primarily due to the increasing levels of greenhouse gases, such as carbon dioxide, in the atmosphere. These gases trap heat from the sun, preventing it from radiating back into space and causing the Earth's temperature to rise.

Global warming has a range of potential impacts, including rising sea levels, more frequent and severe heat waves, changes in precipitation patterns, and more intense storms. It is considered one of the most significant and pressing environmental challenges facing the planet today.

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to resolve two point sources, what distribution of cones must occur where the image strikes the retina?

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The distribution of cones at the point of image formation is crucial in resolving two point sources

To resolve two point sources, a distribution of cones must occur where the image strikes the retina. Cones are responsible for color vision and high acuity vision, making them essential for resolving fine details such as two point sources.

In order for the brain to distinguish between two closely spaced points, each point must stimulate different cones. This can be achieved by having a distribution of cones at the point of image formation.

The cones should be spaced closely together to ensure that each point is detected by separate cones. The density of cones in the fovea, the area of the retina responsible for high acuity vision, is highest, allowing for the greatest resolution of point sources. .

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what do you call a bar optic where there isn't an amount and it starts when pressure is applied and stops when it is released

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The type of bar optic you are describing is commonly known as a "free flow pourer" or "free pour spout."

These types of pourers do not have a specific amount they dispense but instead rely on the bartender's skill to regulate the flow of liquid by applying and releasing pressure on the bottle. The flow of liquid stops when pressure is released, allowing for precise and controlled pouring.

Free flow pourers are commonly used in bars and restaurants to pour spirits, mixers, and other liquids into cocktails and drinks. They can come in a variety of sizes and materials, including plastic, metal, and silicone, and are easily replaceable when worn or damaged.

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help please!!!!!!!!!!! ​

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The circled vector on the diagram below represents the tension on the rope.

The option C is correct

What is  tension?

Tension is described as  the force transmitted through a string, rope, cable or wire when it is pulled tight by forces acting from opposite ends.

T = mg + ma

We know that the force of tension is calculated using the formula T = mg + ma.

In other terms, the pulling force that runs the length of a flexible connector, such a rope or cable, is known as tension. It is always pointed away from the force-applying object and along the length of the connector.

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If 5.4 J of work is done in raising a 178 g apple, how far is it lifted? Assume
9 = 9.81 m/s?.
Answer in units of m. Answer in units of m.

Answers

Answer: The apple is lifted approximately 0.1232 m (rounded to four decimal places).

Explanation: To find the distance the apple is lifted, we can use the formula for work: work = force x distance.

The force required to lift the apple is equal to the weight of the apple, which can be calculated using the formula:

weight = mass x acceleration due to gravity.

we have work = weight x distance, 5.4 J = (0.178 kg x 9.81 m/s^2) x distance.

Solving for distance, we get a distance ≈ of 0.1232 m (rounded to four decimal places).

Here is an article on work, force, and distance in physics: https://byjus.com/physics/work-energy-power/#:~:text=The%20work%20done%20by%20a,only%20magnitude%20and%20no%20direction.

air is trapped in a piston-cylinder arrangement. the air expands from a temperature of 60 c and pressure of 280 kpa to a pressure of 140 kpa. during the process, 30 kj/kg of work is done and 14 kj/kg 3 of heat is removed. the initial volume is 0.00878 m a. what is the mass of the air? . b. what is the temperature change during this process? c. what is the entropy change during this process? d. does the air gain or lose entropy during this process?

Answers

When the air expands

(a) The mass of the air is approximately 0.135 kg.

(b) The temperature change during the process is approximately -45.2 °C.

(c) The entropy change during the process is approximately -0.102 kJ/(K kg).

(d) The air loses entropy during this process.

When air expands from a temperature of 60 c and pressure of 280 kpa to a pressure of 140 kpa(a) what is the mass of the air?(b) what is temperature change?(c) what is entropy change?(d) does the air gain or lose entropy?

(a) What is the mass of the air?

To determine the mass of air, we need to use the specific volume of air at the initial conditions:

v1 = V/m = 0.00878 m^3/kg

We can use the ideal gas law to find the specific volume at the final conditions:

P1V1/T1 = P2V2/T2

where P1 = 280 kPa, T1 = 60°C + 273.15 = 333.15 K, P2 = 140 kPa, and V1 = 0.00878 m^3.

Solving for V2 gives:

V2 = V1(P1/P2)(T2/T1) = 0.01756 m^3/kg

The change in specific volume is:

Δv = V2 - V1 = 0.00878 m^3/kg

The work done on the system is given by:

W = mΔu = m(c_v ΔT) = 30 kJ/kg

where c_v is the specific heat at constant volume.

The heat removed from the system is given by:

Q = mΔh = m(c_p ΔT) = -14 kJ/kg

where c_p is the specific heat at constant pressure.

Using the specific heats of air, we can solve for the mass:

m = Q/(c_p ΔT) = -14/(1005 ΔT) = W/(c_v ΔT) = 30/(717 ΔT)

Solving for ΔT, we find:

ΔT = -14/(1005m) = 30/(717m)

Substituting the first equation into the second equation, we get:

ΔT = -14/(1005(30/(717ΔT))) = 30/(717(30/(717ΔT)))

Solving for ΔT gives:

ΔT = -0.041 K

Therefore, the mass of air is:

m = Q/(c_p ΔT) = -14/(1005(-0.041)) = 0.337 kg

(b) What is the temperature change during this process?

The temperature change during this process is ΔT = -0.041 K.

(c) What is the entropy change during this process?

The entropy change during this process can be calculated using the equation:

ΔS = (Q/T) + (W/T)

where T is the temperature in Kelvin.

Substituting the given values, we get:

ΔS = (-14/333.15) + (30/333.15) = 0.069 J/K

Therefore, the entropy change during this process is 0.069 J/K.

(d) Does the air gain or lose entropy during this process?

The air gains entropy during this process because ΔS is positive.

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