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Conceptual Questions: Work and Conservation of Energy
B
A
D
E
C
1. A cart starts at the top left of the roller coaster shown above. Ignoring air resistance and friction, the farthest
position or region attainable by the cart is:
a. region A
b. position B c. region C
d. position D e. E or beyond
2. A young girl wishes to select one of the frictionless playground slides illustrated below to give her the
greatest possible speed when she reaches the bottom of the slide.
A
B
C
D
Which of the slides illustrated in the diagram should she choose?
a. A
b. B c. C
d. D e. It doesn't matter, her speed would be the same for each.
3. A brick is lifted to a given height and then dropped to the ground. Next, a second identical brick is lifted
half as high as the first and also dropped to the ground. When the second brick strikes the ground it has
a. half as much kinetic energy as the first
b. as much kinetic energy as the first
c. twice as much kinetic energy as the first
d. four times as much kinetic energy as the first
e. impossible to tell
4. A brick is lifted to a given height and then dropped to the ground. Next, a second brick, which weighs twice
as much as the first, is lifted just as high as the first and then it too is dropped to the ground. When the
second brick strikes the ground, it has
a. half as much kinetic energy as the first
b. as much kinetic energy as the first
c. twice as much kinetic energy as the first
d. four times as much kinetic energy as the first
e. impossible to tell
5. If you lift one bag of groceries up five flights of stairs, how much work do you do compared to lifting the
same load up only one flight of stairs?
a. five times as much
b. Twice as much. c. The same amount d. One fifth as much.
493692175
6. As a pendulum swings back and forth,
a. potential energy is transformed into kinetic energy.
b. its energy is all kinetic at the lowest part of its swing.
c. its energy is all potential at hte end points of swing.
d. All of the above.
7. What is the source of energy in sunshine?
8. A friend says the energy of oil and coal is actually a form of solar energy. Is your fiend correct or mistaken?
9. Why is it easier to stop a lightly loaded truck than a heavier one that has equal speed?
10. Robin Hood wants to shoot an arrow using a bow. To determine the potential energy of the drawn bow,
would it be an underestimate or an overestimate to multiply the force with which he holds the arrow in its
drawn position by the distance she pulled it? Why do we say the work done is the average force x distance?
11. Why do long-range cannons have such long barrels?
12. You and a flight attendant toss a ball back and forth in an airplane in flight. Does the KE of the ball depend
on the speed of the airplane? Explain.
13.
When the mass of a moving object is doubled with no change in speed, by what factor is its kinetic energy
changed?
14. You have a choice of catching a baseball or a bowling ball, both with the same KE. Which is safer?
15. Why does the force of gravity do no work on a bowling ball rolling along a bowling alley? A satellite in
circular orbit around the Earth?
16. A crate is pulled across a horizontal floor by a rope. At the same time, the crate pulls back on the rope, in
accord with Newton’s third law. Does the work done on the crate by the rope then equal zero? Explain.
17. On a slide a child has potential energy that decreases by 100 J while her kinetic energy increases by 900 J.
What other form of energy is involved, and how much?
18. Consider a ball thrown straight up in the air. At what position is its kinetic energy at a maximum? Where is
its gravitational potential energy a maximum?
19. An apple hanging from a limb has potential energy because of its height. If it falls, what becomes of this
energy just before it hits the ground? When it hits the ground?
20. With what force does a rock that weighs 10 N strike the ground if dropped from a rest position 10 m high?
In fact, the question cannot be answered unless you know more. Why?
21.
How can work be done when the net force equals zero?
22. A stone is dropped from a certain height and penetrates into mud. All else being equal, if it is dropped from
twice the height, how much farther should it penetrate?
493692175
Conceptual Questions: Work and Conservation of Energy
B
A
D
E
C
1. A cart starts at the top left of the roller coaster shown above. Ignoring air resistance and friction,
the farthest position or region attainable by the cart is:
a. region A
b. position B c. region C
d. position D e. E or beyond
2. A young girl wishes to select one of the frictionless playground slides illustrated below to give her the
greatest possible speed when she reaches the bottom of the slide.
A
B
C
D
Which of the slides illustrated in the diagram should she choose?
a. A
b. B c. C
d. D e. It doesn't matter, her speed would be the same for each.
3. A brick is lifted to a given height and then dropped to the ground. Next, a second identical brick is lifted
half as high as the first and also dropped to the ground. When the second brick strikes the ground it has
a. half as much kinetic energy as the first
b. as much kinetic energy as the first
c. twice as much kinetic energy as the first
d. four times as much kinetic energy as the first
e. impossible to tell
4. A brick is lifted to a given height and then dropped to the ground. Next, a second brick, which weighs twice
as much as the first, is lifted just as high as the first and then it too is dropped to the ground. When the
second brick strikes the ground, it has
a. half as much kinetic energy as the first
b. as much kinetic energy as the first
c. twice as much kinetic energy as the first
d. four times as much kinetic energy as the first
e. impossible to tell
5. If you lift one bag of groceries up five flights of stairs, how much work do you do compared to lifting the
same load up only one flight of stairs?
a. five times as much
b. Twice as much. c. The same amount d. One fifth as much.
493692175
6. As a pendulum swings back and forth,
a. potential energy is transformed into kinetic energy.
b. its energy is all kinetic at the lowest part of its swing.
c. its energy is all potential at the end points of swing.
d. All of the above.
7. What is the source of energy in sunshine?
8. A friend says the energy of oil and coal is actually a form of solar energy. Is your fiend correct or mistaken?
9. Why is it easier to stop a lightly loaded truck than a heavier one that has equal speed?
10. Robin Hood wants to shoot an arrow using a bow. To determine the potential energy of the drawn bow,
would it be an underestimate or an overestimate to multiply the force with which he holds the arrow in its
drawn position by the distance she pulled it? Why do we say the work done is the average force x distance?
11. Why do long-range cannons have such long barrels?
12. You and a flight attendant toss a ball back and forth in an airplane in flight. Does the KE of the ball depend
on the speed of the airplane? Explain.
13.
When the mass of a moving object is doubled with no change in speed, by what factor is its kinetic energy
changed?
14. You have a choice of catching a baseball or a bowling ball, both with the same KE. Which is safer?
15. Why does the force of gravity do no work on a bowling ball rolling along a bowling alley? A satellite in
circular orbit around the Earth?
16. A crate is pulled across a horizontal floor by a rope. At the same time, the crate pulls back on the rope, in
accord with Newton’s third law. Does the work done on the crate by the rope then equal zero? Explain.
17. On a slide a child has potential energy that decreases by 100 J while her kinetic energy increases by 900 J.
What other form of energy is involved, and how much?
18. Consider a ball thrown straight up in the air. At what position is its kinetic energy at a maximum? Where is
its gravitational potential energy a maximum?
19. An apple hanging from a limb has potential energy because of its height. If it falls, what becomes of this
energy just before it hits the ground? When it hits the ground?
20. With what force does a rock that weighs 10 N strike the ground if dropped from a rest position 10 m high?
In fact, the question cannot be answered unless you know more. Why?
21.
How can work be done when the net force equals zero?
22. A stone is dropped from a certain height and penetrates into mud. All else being equal, if it is dropped from
twice the height, how much farther should it penetrate?
493692175