As a 5.00-kg sample of liquid mercury is cooled into a solid, it liberates 157 kJ of energy. What is the original temperature of the mercury? For mercury, the melting point is 234 K, the heat of fusion is 11.3 kJ/kg,
and the specific heat is 140 J/kg . K.

378 K
690 K
157 K
410 K

Answers

Answer 1

The original temperature of the mercury is 260.6K

Here is how to arrive at temperature of the mercury

To solve this problem, we can use the formula for the heat released during the solidification of a substance:

Q = m * Lf

where Q is the heat released, m is the mass of the substance, and Lf is the heat of fusion of the substance.

In this case, Q = 157 kJ, m = 5.00 kg, and Lf = 11.3 kJ/kg.

We also need to use the formula for the heat absorbed or released during a temperature change:

Q = m * c * ΔT

where Q is the heat absorbed or released, m is the mass of the substance, c is the specific heat of the substance, and ΔT is the change in temperature.

We can use this formula to calculate the heat released as the mercury cools from its original temperature to its melting point, and then use the formula for solidification to calculate the heat released as the mercury solidifies.

Let T be the original temperature of the mercury.

The heat released as the mercury cools from its original temperature to its melting point is:

Q1 = m * c * (T - 234)

The heat released as the mercury solidifies is:

Q2 = m * Lf

The total heat released is:

Q = Q1 + Q2 = m * c * (T - 234) + m * Lf

Substituting the values given in the problem, we get:

157 kJ = 5.00 kg * 140 J/kg . K * (T - 234) + 5.00 kg * 11.3 kJ/kg

Simplifying and solving for T, we get:

T = 260.6 K

Therefore, the original temperature of the mercury was 260.6 K.

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Related Questions

a wave has a frequency of 40 hertz and a wavelength of 2 meters . what is the wave speed ?

Answers

Answer:

[tex]80\; {\rm m\cdot s^{-1}}[/tex].

Explanation:

The frequency [tex]f[/tex] of a wave is the number of cycles completed in unit time ([tex]1\; {\rm s}[/tex] in this example.) In this question, [tex]f = 40\; {\rm s^{-1}}[/tex] ([tex]1\; {\rm Hz} = 1\; {\rm s^{-1}}[/tex]) means that the wave would complete [tex]40[/tex] cycles in every [tex]1\; {\rm s}[/tex].

The wavelength [tex]\lambda[/tex] of a wave is the distance the wave travels in each cycle. It is given that [tex]\lambda = 2\; {\rm m}[/tex].

The goal is to find the wave speed, which is the distance that this wave travels in unit time ([tex]1\; {\rm s}[/tex].)

In this question, it is given that [tex]\lambda = 2\; {\rm m}[/tex] and [tex]f = 40\; {\rm s^{-1}}[/tex]. Thus, this wave would travel a total of [tex]40\, (2\; {\rm m}) = 80\; {\rm m}[/tex] for the [tex]40[/tex] cycles completed in each unit time of [tex]1\; {\rm s}[/tex] ([tex]\lambda = 2\; {\rm m}[/tex] for each cycle.) The speed of this wave would be [tex]80\; {\rm m\cdot s^{-1}}[/tex].

Formally, the speed [tex]v[/tex] of this wave can be found by multiplying the wavelength [tex]\lambda[/tex] of this wave by its frequency [tex]f[/tex]:

[tex]\begin{aligned}v &= \lambda\, f \\ &= (2\; {\rm m})\, (40\; {\rm s^{-1}) \\ &= 80\; {\rm m\cdot s^{-1}}\end{aligned}[/tex].

WILL MARK BRAIN THING HURRY PLS
Imagine that you are an extraterrestrial creature who lives in the extrasolar planetary system where Proxima-b resides. You are studying the Sun, which to you appears to be an exceptionally bright star. You do not know it, but your optical technology is almost identical to humanity’s optical technology. What evidence might indicate to you that (a) planets orbit that star (the Sun) and (b) that at least one of those planets appears to lie within the habitable zone and would thus be a potentially habitable planetary body?

Answers

a.) The evidence for planets orbiting the Sun might be :

Periodic variations in the brightness of the SunChanges in the position of the star

b.  Evidence for potentially habitable planets might come in the form of

Transit observationsSpectral observations

What is meant by planets?

A planet is described as a celestial body that is in orbit around the Sun, has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and  has cleared the neighborhood around its orbit.

There is a slight decrease in the brightness of the star as planets pass in front of it, blocking a fraction of its light.

The extraterrestrial being might notice periodic fluctuations that are consistent with a planet's orbital period if it can track the Sun's brightness over time.

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A large piston in a hydraulic lift has an area of 100 cm2. The force needed to a small piston with an area of 15 cm2 to lift a 1800 kg car is _ kg

Answers

The force needed to lift the 1800 kg car with the small piston is 2,649 N or approximately 270 kg (since 1 kg is equal to 9.81 N).  

The hydraulic lift works based on Pascal's principle, which states that the pressure applied to a confined fluid is transmitted equally in all directions throughout the fluid.

Assuming there is no loss of energy due to friction or other factors, the force exerted on the small piston will be equal to the force exerted on the large piston. This can be expressed as:

F1/A1 = F2/A2

where F1 is the force exerted on the large piston, A1 is the area of the large piston, F2 is the force exerted on the small piston (which we want to find), and A2 is the area of the small piston.

We can rearrange this equation to solve for F2:

F2 = (F1/A1) x A2

Given that the area of the large piston is 100 cm², we can calculate the force exerted on the large piston by using the weight of the car and the gravitational acceleration:

F1 = m x g = 1800 kg x 9.81 m/s² = 17,658 N

Substituting the values into the equation, we get:

F2 = (17,658 N / 100 cm2) x 15 cm² = 2,649 N

Therefore, the force needed to lift the 1800 kg car with the small piston is 2,649 N or approximately 270 kg (since 1 kg is equal to 9.81 N).

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If the sun were more massive, what would happen to Earth’s gravity with the sun?
A. decrease
B. would be infinite
C. would be 0
D. increase

Answers

Answer: d. increase

Explanation:

If the sun were more massive, the gravitational force between the sun and Earth would increase. This means that Earth's gravity with the sun would also increase. Therefore, the correct answer is (D) increase.

The gravitational force between two objects is directly proportional to the product of their masses and inversely proportional to the square of the distance between them. So, if the mass of one of the objects increases, the gravitational force between them will also increase. In this case, if the mass of the sun were to increase, the gravitational force between the sun and Earth would become stronger, and hence, Earth's gravity with the sun would also increase.

A light ray passing through air strikes the surface of a glass block (n=1.5) and makes 30° angle of incidence. How many degrees will the light ray deviate from its original path after refraction?​

Answers

The light ray will deviate from its original path with 19.5° after refraction.

How do we calculate?

Applying Snell's law to calculate the angle of refraction:

n1 sin θ1 = n2 sin θ2

where n1 and θ1 =  the refractive index and the angle of incidence in the first medium (air),

n2 and θ2 =  the refractive index and the angle of refraction in the second medium (glass).

In this example,

n1 = 1.00 (refractive index of air), θ1 = 30°, and

n2 = 1.5 (refractive index of glass).

We then calculate for  θ2:

n1 sin θ1 = n2 sin θ2

1.00 * sin 30° = 1.5 * sin θ2

0.5 = 1.5 * sin θ2

sin θ2 = 0.5 / 1.5 = 1/3

θ2 = sin^-1(1/3)

θ2 = 19.5°

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How loud in Decibels would a sound be with an intensity of 7.8x10^-4 W/m2? (write your answer to one decimal space)

Answers

A sound that is 7.8x10-4 W/m2 in intensity is equal to (10 dB)log3.2106 W/m21012 W/m2=185 dB.

How can you determine the relative volume of a sound?

The decibel, often known as the db or 0.1 bel, is the standard measurement unit. Hence, b = 10 log10 (I/I0) can be used to express the relationship between relative intensities, or b, in decibels. This equation can be used to determine that one decibel equals a 26 percent intensity variations.

What does physics mean by relative intensity?

The "decibel level" of a sound is a less formal term for relative intensity level. It is not the same as energy; relative intensity level reflects loudness more faithfully by using a logarithmic scale.

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According to this graph, the acceleration
is approximately:
A. 12 m/s²
C. 4 m/s²
Velocity (m/s)
14
12
10
12 2 3 4
Time t (s)
B. 1.5 m/s2
D. 3 m/s2

Help please

Answers

Answer:

Explanation:

Because you have velocity along the y axis and time along the x axis, this is a velocity v time graph which is an acceleration graph. The slope of the line in this graph IS the acceleration. We can use 2 points and the slope formula to solve for the acceleration:

(0, 0) and (1, 3):

[tex]m=\frac{3-0}{1-0}=3[/tex] m/s squared, choice D.

How long does it take for radiation from a cesuim-133 atom to complete 1.5 million cycles

Answers

A cesium-133 atom's radiation goes through 1.5 million cycles in around 0.1633 microseconds (or 163.3 nanoseconds).

What frequency does one kind of radiation that cesium-133 emits have?

9,192,631,770 hertz (cycles per second) is the frequency of the microwave spectral line that the isotope cesium-133 emits. The basic unit of time is provided by this. Cesium clocks have an accuracy and stability of 1 second in 1.4 million years.

The radiation emitted by cesium-133 has a frequency of 9,192,631,770 cycles per second, or 9.192631770 109 Hz.

The following formula may be used to determine how long 1.5 million radiation cycles take to complete:

Time is equal to the frequency of cycles.

Plugging in the numbers, we get:

time = 1.5 million / 9.192631770 × 10^9 Hz

time = 1.632995101 × 10^-7 seconds

So it takes approximately 0.1633 microseconds (or 163.3 nanoseconds) for radiation from a cesium-133 atom to complete 1.5 million cycles.

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can you please tell me where does 1-14 i really need help thanks :) god bless you all

Answers

The above has to do with the study of the earth's lithospheric plates. See the attached image and the explanation below.

What are the processes of the movement of lithospheric plates?

The movement of lithospheric plates is a geological process that occurs due to the motion of hot, molten material in the Earth's mantle. The lithosphere, which is the rigid outer layer of the Earth's surface, is divided into several large plates that move relative to each other.

These movements are caused by the convection of material in the mantle and the forces that arise at the boundaries between the plates.

There are three main types of plate boundaries: divergent, convergent, and transform. Divergent boundaries occur where plates move apart from each other, creating new oceanic crust. Convergent boundaries arise where plates collide, leading to subduction, volcanic activity, and the formation of mountains. Transform boundaries occur where plates slide past each other.

The movement of lithospheric plates gives rise to various geological phenomena, such as earthquakes, volcanic activity, and the formation of mountain ranges and ocean basins.

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A U-tube is open to the atmosphere at both ends. Water is poured into the tube until the water rises part-way along the straight sides, and then some oil with a density of is poured into one end. This causes the water surface on that side of the tube to go down by and the surface on the other side to go up by the same amount. How much higher is the top surface of the oil on that side of the tube compared with the surface of the water on the other side of the tube?

Answers

The top surface of the oil on that side of the tube is 0.6 times higher than the surface of the water on the other side of the tube.

Describe principle of hydrostatics?

The principle of hydrostatics, also known as Pascal's principle, states that when an external pressure is applied to a fluid in a container, that pressure is transmitted uniformly in all directions within the fluid, regardless of the shape or volume of the container. In other words, the pressure applied to a confined fluid will be distributed evenly throughout the fluid and will not change in magnitude at any point within the fluid. This principle is important in a number of applications, such as hydraulic systems, which use fluids to transmit force and pressure from one point to another. It is also used to explain how liquids exert pressure on the walls of their container and how objects can float or sink in fluids.

We can use the principles of hydrostatics to solve this problem. Let's call the height difference between the two water surfaces h. We can assume that the oil completely covers the water on one side of the tube and does not mix with it, so the oil and water form two separate liquid columns with a common interface. Let's call the height difference between the oil and water surfaces on the same side of the tube H.

The pressure at any given point in a fluid depends only on the depth of that point below the surface of the fluid and the density of the fluid. Since the two water columns are at the same height, they experience the same pressure from the atmosphere. Similarly, the two oil columns experience the same pressure from the atmosphere.

Now consider a point on the interface between the oil and water on the same side of the tube. This point is at a depth of h+H below the water surface on the other side of the tube, so the pressure at this point is greater than atmospheric pressure by an amount equal to the product of the density of water, the acceleration due to gravity, and the total depth (h+H):

P = Patm + ρwatergh

where P is the pressure at the interface, Patm is atmospheric pressure, ρwater is the density of water, g is the acceleration due to gravity, and h+H is the total depth.

Similarly, the pressure at this point is less than atmospheric pressure by an amount equal to the product of the density of oil, the acceleration due to gravity, and the depth of the oil column (H):

P = Patm - ρoilgH

Since the interface between the oil and water is at the same pressure, we can equate these two expressions for P:

Patm + ρwatergh = Patm - ρoilgH

Solving for H, we get:

H = h(ρwater/ρoil)

Substituting the given values, we get:

H = 0.6h

Therefore, the top surface of the oil on that side of the tube is 0.6 times higher than the surface of the water on the other side of the tube.

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What would be the intensity of a sound wave produced by a 150 Watt speaker from a distance of 5.8 meters? (write your answer to two digits)

Answers

The relationship between a sound wave's intensity and pressure amplitude (also known as pressure variation p) is. I is equal to (p) 2 2 v w, where is the thickness of the substance that the sound is contained in.

Describe a sound wave.

Hence, a sound wave is made up of periodically occurring compressions and compression and rarefaction, or areas of high and low pressure, that are travelling at a specific pace. In other words, it consists of a regular (i.e., oscillating or vibrating) change in pressure that takes place around the optimum pressure that is present at a specific time and location.

A sound wave is created by a speaker in what way?

A speaker creates a sound by vibrating a cone, which causes air molecules to vibrate. A speaker in Figure 17.2. 2 vibrates with a consistent frequency and amplitude, causing motions in the molecules of the surrounding air. The speaker transfers power to the air as it vibrates back and forth, primarily as thermal energy.

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A 0.80kg block of carbon (solid) is dropped into 1.4kg of water. If the carbon starts at -20C, the water starts at 92C, and they have equal final temperatures, what is the final temperature of the system?

Answers

The system's final temperature is roughly 16.7°C.

What is a system's final temperature?

You may determine your substance's final heat by multiplying the temperature change by the initial temperature. Your water's final temperature would be 24 + 6, or 30 degrees Celsius, for instance, if it started off at 24 degrees Celsius.

The following is the formula for energy conservation:

Q1 + Q2 = 0

Q = mcΔT

Q1 + Q2 = 0

568.8

Simplifying and solving for

6394.4 - 106768 = 0

= 16.7°C

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A rock climber stands on top of a 59 m -high cliff overhanging a pool of water. He throws two stones vertically downward 1.0 s apart and observes that they cause a single splash. The initial speed of the first stone was 1.7 m/s . Include value and units.
a) How long after the release of the first stone does the second stone hit the water?
b) What was the initial speed of the second stone?
c) What is the speed of the first stone as it hits the water?
d) What is the speed of the second stone as it hits the water?

Answers

a) The time after the release of the first stone that the second stone hits the water is 2.0 s.

b) 15.7 m/s is the initial speed of the second stone.

c)  The speed of the first stone as it hits the water is 15.7 m/s.

d) The speed of the second stone as it hits the water is 28.2 m/s.

What is velocity?

Velocity is a vector quantity that measures both the speed and direction of an object's motion. It is equal to the rate of change of an object's position with respect to time. Velocity is usually represented by the symbol v and is measured in meters per second (m/s).

a) The time between first and second stone's release is 1.0 s. Since the time of release of first stone and the time of splash of both stones are same, the time between the release of second stone and the splash of both stones is 1.0 s.

Thus, the time after the release of the first stone that the second stone hits the water is 2.0 s.

b) The initial speed of the second stone can be calculated using the equation of motion,

v² = u² + 2as

where v is the final velocity, u is the initial velocity, a is the acceleration due to gravity (9.8 m/s²), and s is the displacement.

Substituting the values,

v² = (1.7)² + 2(9.8) * 59

v = 15.7 m/s

c) The speed of the first stone as it hits the water can be calculated using the equation of motion,

v² = u² + 2as

where v is the final velocity, u is the initial velocity, a is the acceleration due to gravity (9.8 m/s²), and s is the displacement.

Substituting the values,

v² = (1.7)² + 2(9.8) * 59

v = 15.7 m/s

d) The speed of the second stone as it hits the water can be calculated using the equation of motion,

v² = u² + 2as

where v is the final velocity, u is the initial velocity, a is the acceleration due to gravity (9.8 m/s²), and s is the displacement.

Substituting the values,

v² = (15.7)² + 2(9.8) * 59

v = 28.2 m/s

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5. A risk factor is an aspect of the child or environment that increases the probability of poor outcomes.
Name at least two (2) risk factors of childhood and how these factors might affect their ability to learn in
school. (2 Points)


Anyone pls

Answers

The two risk factors that can affect the ability of a child to learn in school is poor parenting and malnutrition.

What is a risk factor?

A risk factor can be defined as any predisposing factor that can expose an individual to harm.

A risk factor that affects a child is an aspect of the child or environment that increases the probability of poor outcomes.

The two risk factors that can affect the ability of a child to learn in school include the following:

Poor parenting: When there is lack of understanding and love between the couple is affects the emotions of the children.Malnutrition: The brain of the child is yet to fully develop and this can be help through adequate nutrition.

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5. Two equal charges are situated in a vacuum 10.0cm apart, if they repel each other with a force of 0.5N, calculate the value of the charge on each. [4π)¹ = 9.0 x 10⁹ I​

Answers

The value of the charge on each particle is [tex]1.05 x 10^-8 C[/tex].

What is Coulomb's law?

Coulomb's law is a fundamental principle of electrostatics that describes the interaction between electric charges. It states that the force between two point charges is directly proportional to the product of their charges and inversely proportional to the square of the distance between them. We can use Coulomb's law to solve this problem. Mathematically,

[tex]F = k(q1q2)/r^2[/tex]

where F is the force of attraction or repulsion between the two charged particles,[tex]q1[/tex] and [tex]q2[/tex] are the magnitudes of the charges on the two particles, r is the distance between them, and k is Coulomb's constant, which has a value of [tex]9.0 x 10^9 Nm^2/C^2.[/tex]

In this problem, we know that the charges are equal and the distance between them is 10.0 cm. We also know that the force between them is 0.5 N. Therefore,

[tex]0.5 N = k(q^2)/(0.1 m)^2[/tex]

Solving for q, we get:

[tex]q = \sqrt{[(0.5 N)(0.1 m)^2/k]}[/tex]

[tex]q = \sqrt{(0.5 N)(0.01 m)/(9.0 x 10^9 Nm^2/C^2)}[/tex]

[tex]q = 1.05 x 10^-8 C[/tex]

Therefore, the value of the charge on each particle is [tex]1.05 x 10^-8 C.[/tex]

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I need help please thank you .:)

Answers

Protons, neutrons, and electrons are the three main subatomic particles that make up atoms.

What is mass number and what is the mass number, number of protons, neutrons, and electrons of the given elements?

An oxygen atom has 8 protons, 8 electrons, and its number of neutrons may vary depending on the isotope of oxygen. The more frequently encountered isotope of oxygen is oxygen-16, with 8 neutrons.

The element with 13 protons is aluminum (Al). To find the mass number, we add the number of protons and neutrons in the nucleus. Therefore, the mass number of this aluminum isotope would be 13 + 14 = 27.

If an atom has 7 electrons, it must be nitrogen (N), which has an atomic number of 7.

Number of neutrons = Mass number - Atomic number

Thus, we obtain the number of neutrons by the equation: 14 - 7 = 7

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The attractive electric force between the point charges q and −2q has a magnitude of 2.2 N when the separation between the charges is 1.4 m . k=8.99×109N⋅m2/C2

What is the magnitude of charge q?

Answers

The electric force between two point charges is given by the equation

[tex]F=k*q_1*q_2/r^2[/tex]

What is force?

The interaction between two things is measured by the physical quantity known as force. It is a vector quantity, and the sign F is frequently used to denote it. When an object interacts with another object, it feels a push or a pull.

where r is the distance between the charges, q1 and q2 are their magnitudes, and k is the Coulomb constant.

When we enter the problem's specified values, we obtain

[tex]2.2N=8.99*10^9\ N*m^2/C^2*q*-2q/(1.4 m)^2[/tex]

which simplifies to

q = -0.500 N/C.

Thus, the magnitude of charge q is 0.500 N/C.

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please help me in this exercise​

Answers

a. We can actually see here that the girl have kinetic energy which is respect to the escalator.

b. The kinetic energy does not depend on the chosen reference.

What is kinetic energy?

Kinetic energy is a form of energy that an object possesses due to its motion. It is defined as the work needed to accelerate a body of a given mass from rest to its current velocity. Kinetic energy is a scalar quantity, meaning it only has magnitude and no direction. The formula for calculating kinetic energy is:

KE = 1/2 × m × v²

Where KE is the kinetic energy, m is the mass of the object, and v is its velocity.

The concept of kinetic energy was first introduced by the French mathematician Gaspard-Gustave de Coriolis in 1829. It was later developed by other scientists such as James Prescott Joule and Hermann von Helmholtz.

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Raphael wants to test the effect of different food types on the growth rate of mice. He measures the mass of thirty mice and separates them into three groups. Each group is given a different type of feed. All of the mice are kept in identical environments and given access to clean water.

After three months, Raphael measures the mass of the mice again. The results of Raphael's experiment are shown below.

Food Type Average Growth (g)
oat grains 1.5 g
cereal flakes 0.3 g
sunflower seeds 2.1 g


Which of the following is a fact that Raphael can determine from his experiment?
A.
Mice do not like the taste of cereal flakes.
B.
Sunflower seeds are the best type of food to feed pet mice.
C.
Mice that ate sunflower seeds gained an average of 2.1 grams.
D.
Bigger mice are more desirable as pets than smaller mice.

Answers

Mice that ate sunflower seeds gained an average of 2.1 grams that Raphael can determine from his experiment. Each group is given a different type of feed.

What is grams ?

Grams (g) is a unit of measurement for mass in the International System of Units (SI). It is the base unit of mass in the SI, and is defined as being equal to the mass of a physical prototype, which is kept at the International Bureau of Weights and Measures. In practical terms, 1 gram is equal to 0.0352739619 ounces, or 0.00220462262 pounds. Grams are often used to measure the weight of food, medicines, and other small objects.

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The length of the river span of a bridge is 2799.0 ft. The total length of the bridge is 6998ft. Convert the length of the river span of the bridge to meters.

Answers

According to the question the length of the river span of the bridge in meters is 853.3232 m.

What is Length?

Length is a physical quantity that measures the distance between two points. It is one of the fundamental units in the International System of Units (SI). It is usually measured in meters, although it can also be measured in other units such as centimeters, kilometers, feet, yards, miles, and so on.

The length of the river span of the bridge is 2799.0 ft. To convert this length to meters, we need to use a conversion factor. There are 0.3048 meters in one foot, so the conversion factor we will use is 1 ft
= 0.3048 m.

To convert 2799.0 ft to meters, we multiply by the conversion factor:
2799.0 ft * 0.3048 m/ft
= 853.3232 m

Therefore, the length of the river span of the bridge in meters is 853.3232 m.

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A 25 kg child plays on a swing having support ropes that are 2.20 m long. A friend pulls her back until the ropes are ăÿÿfrom the vertical and releases her from rest. (a) What is the potential energy for the child just as she is released compared with the potential energy at the bottom of the swing? (b) How fast will she be moving at the bottom of the swing? (c) How much work does the tension in the ropes do as the child swings from the initial position to the bottom?

Answers

Answer:

A) P.E = 138.44 J

B) The velocity of swing at bottom, v = 3.33 m/s

C) The work done, W = -138.44 J

Explanation:

Given,

The mass of the child, m = 25 Kg

The length of the swing rope, L = 2.2 m

The angle of the swing to the vertical position, ∅ = 42°

A) The potential energy at the initial position ∅ = 42° is given by the relation

                               P.E = mgh joule

Considering h  = 0 for the vertical position

The h at ∅ = 42° is  h = L (1 - cos∅)

                              P.E = mgL (1 - cos∅)

Substituting the given values in the above equation

                              P.E = 25 x 9.8 x 2.2 (1 - cos42°)

                                     = 138.44 J

The potential energy for the child just as she is released, compared to the potential energy at the bottom of the swing is, P.E = 138.44 J

B) The velocity of the swing at the bottom.

At bottom of the swing the P.E is completely transformed into the K.E

                 ∴                 K.E = P.E

                                    1/2 mv² = 138.44

                                    1/2 x 25 x v² 138.44

                                           v² = 11.0752

                                            v = 3.33 m/s

The velocity of the swing at the bottom is, v = 3.33 m/s

C) The work done by the tension in the rope from initial position to the bottom

            Tension on string, T = Force acting on the swing, F

                     

                           

                           =

                           = - 2.2 x 25 x 9.8 [cos0 - cos 42°]

                           = - 138.44 J

The negative sign in the in energy is that the work done is towards the gravitational force of attraction.

The work done by the tension in the ropes as the child swings from the initial position to the bottom of the swing, W = - 138.44 J

We can use conservation of energy to solve this problem. At the initial position, the child has no kinetic energy and all her energy is potential energy due to her height above the lowest point of the swing. At the bottom of the swing, the child has no potential energy and all her energy is kinetic energy due to her speed.

(a) The potential energy of the child just as she is released can be calculated as:
PE = mgh
where m is the mass of the child, g is the acceleration due to gravity, and h is the height of the child above the lowest point of the swing. At the initial position, h = 2.20 m, so the potential energy is:
PE_initial = mgh = (25 kg)(9.81 m/s^2)(2.20 m) = 544 J

At the bottom of the swing, h = 0, so the potential energy is zero:
PE_bottom = 0 J

The potential energy at the initial position is greater than the potential energy at the bottom of the swing, since the child loses potential energy as she swings down.

(b) We can use conservation of energy to find the speed of the child at the bottom of the swing. At the initial position, all the energy is potential energy. At the bottom of the swing, all the energy is kinetic energy. Therefore, the potential energy at the initial position is equal to the kinetic energy at the bottom of the swing:
PE_initial = KE_bottom
mgh = (1/2)mv^2
where v is the speed of the child at the bottom of the swing. Solving for v, we get:
v = sqrt(2gh)
where sqrt means square root. Substituting the values, we get:
v = sqrt(2(9.81 m/s^2)(2.20 m)) = 6.26 m/s

Therefore, the child will be moving at a speed of 6.26 m/s at the bottom of the swing.

(c) The work done by the tension in the ropes as the child swings from the initial position to the bottom can be found as the change in the total mechanical energy of the child:
W = ΔE = KE_bottom - PE_initial
Substituting the values, we get:
W = (1/2)mv^2 - mgh
W = (1/2)(25 kg)(6.26 m/s)^2 - (25 kg)(9.81 m/s^2)(2
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