# Mastering Physics 7

## Unlock all answers in this set

question
distance / kinetic
The work-energy theorem states that a force acting on a particle as it moves over a ______ changes the ______ energy of the particle if the force has a component parallel to the motion. Choose the best answer to fill in the blanks above: distance / potential distance / kinetic vertical displacement / potential none of the above
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distance
To calculate the change in energy, you must know the force as a function of _______. The work done by the force causes the energy change. Choose the best answer to fill in the blank above: acceleration work distance potential energy
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force / kinetic
To illustrate the work-energy concept, consider the case of a stone falling from xi to xf under the influence of gravity. Using the work-energy concept, we say that work is done by the gravitational _____, resulting in an increase of the ______ energy of the stone. Choose the best answer to fill in the blanks above: force / kinetic potential energy / potential force / potential potential energy / kinetic
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change / potential
Rather than ascribing the increased kinetic energy of the stone to the work of gravity, we now (when using potential energy rather than work-energy) say that the increased kinetic energy comes from the ______ of the _______ energy. Choose the best answer to fill in the blanks above: work / potential force / kinetic change / potential
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sum / conserved
his process happens in such a way that total mechanical energy, equal to the ______ of the kinetic and potential energies, is _______. Choose the best answer to fill in the blanks above: sum / conserved sum / zero sum / not conserved difference / conserved
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Wd = 1/2mv^2?mgd
What is the work Wd done on the skydiver, over the distance d, by the drag force of the air? Express the work in terms of d, v, m, and the magnitude of the acceleration due to gravity g.
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Pd = -mgv
Find the power Pd supplied by the drag force after the skydiver has reached terminal velocity v. Express the power in terms of quantities given in the problem introduction.
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d = mg/k+L
How far below the bridge will Kate eventually be hanging, once she stops oscillating and comes finally to rest? Assume that she doesn't touch the water. Express the distance in terms of quantities given in the problem introduction.
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k = 2mgh(h?L)2
If Kate just touches the surface of the river on her first downward trip (i.e., before the first bounce), what is the spring constant k? Ignore all dissipative forces. Express k in terms of L, h, m, and g.
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at its maximum value at the lowest point of the track.
Where on the track is the skater's kinetic energy the greatest? The skater's kinetic energy is at its maximum value at the lowest point of the track. the same everywhere. at its maximum value at the locations where the skater turns and goes back in the opposite direction.
question
at its maximum value at the locations where the skater turns and goes back in the opposite direction.
Change the Energy vs. Position graph to display only potential energy. As the skater is skating back and forth, where does the skater have the most potential energy? The skater's potential energy is at its maximum value at the locations where the skater turns and goes back in the opposite direction. at its maximum value at the lowest point of the track. the same everywhere.
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the same at all locations of the track.
Display the total energy in the Energy vs. Position graph. As the skater is skating back and forth, which statement best describes the total energy? The total energy is smallest at the locations where the skater turns to go back in the opposite direction and greatest at the lowest point of the track. the same at all locations of the track. greatest at the locations where the skater turns and goes back in the opposite direction and smallest at the lowest point of the track.
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equal to the amount of potential energy loss in going from the initial location to the bottom
Based on the previous question, which statement is true? The kinetic energy at the bottom of the ramp is equal to the initial potential energy. equal to the amount of potential energy loss in going from the initial location to the bottom. equal to the total energy.
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2205 J
If the skater started from rest 4 m above the ground (instead of 7m), what would be the kinetic energy at the bottom of the ramp (which is still 1 m above the ground)? 2205 J 4410 J 2940 J 735 J
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11 m/s
Tne common application of conservation of energy in mechanics is to determine the speed of an object. Although the simulation doesn't give the skater's speed, you can calculate it because the skater's kinetic energy is known at any location on the track. Consider again the case where the skater starts 7 m above the ground and skates down the track. What is the skater's speed when the skater is at the bottom of the track?
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higher, but less than twice as fast.
When the skater starts 7 m above the ground, how does the speed of the skater at the bottom of the track compare to the speed of the skater at the bottom when the skater starts 4 m above the ground? The speed is the same. higher, but less than twice as fast. twice as fast. four times as fast.
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equal to zero.
Change the potential energy reference line to be 7 m above the ground (select the Potential Energy Reference option, and click and drag on the dashed blue horizontal line to the 7 m grid line). Place the skater on the track 7 m above the ground, and let the skater go. The total energy of the skater is greater than zero. less than zero. equal to zero.
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the same as the case when the potential energy reference was the ground.
At the bottom of the hill, how does the kinetic energy compare to the case when the potential energy reference was the ground and the skater was released 7m above the ground? The kinetic energy is the same as the case when the potential energy reference was the ground. greater than the case when the potential energy reference was the ground. less than the case when the potential energy reference was the ground.
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directed to the left
The force acting on the particle at point A is __________. directed to the right directed to the left equal to zero
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directed to the right
The force acting on the particle at point C is __________. directed to the right directed to the left equal to zero
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equal to zero
The force acting on the particle at point B is __________. directed to the right directed to the left equal to zero
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equal to zero
The acceleration of the particle at point B is __________. directed to the right directed to the left equal to zero
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directed to the left
If the particle is located slightly to the left of point B, its acceleration is __________. directed to the right directed to the left equal to zero
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directed to the right
f the particle is located slightly to the right of point B, its acceleration is __________. directed to the right directed to the left equal to zero
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B,F
Name all labeled points on the graph corresponding to unstable equilibrium.
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D, H
Name all labeled points on the graph corresponding to stable equilibrium
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B,D,F,H
Name all labeled points on the graph where the acceleration of the particle is zero.
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A, E