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Conceptual Questions: Conservation of Energy
B
D
A
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
3. Which of the slides illustrated in the diagram should she choose?
a. A
b. B
c. C
d. D
e. Speed would be the same
4. 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
5. 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
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.
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7. When the mass of a moving object is doubled with no change in speed, by what factor is its kinetic
energy changed?
8. Consider a ball thrown straight up in the air.
a. At what position is its kinetic energy at a maximum?
b. Where is its gravitational potential energy a maximum?
9. What factors determine the gravitational potential energy that an object has?
10. Why should you be more worried about a piano falling from the 2nd story than about a flowerpot falling
off the 2nd story?
11. What factors determine the kinetic energy that an object has?
12. A rock sitting at the edge of a cliff contains energy called ______________ energy.
a. potential
b. kinetic
c. chemical
d. solar
e. electrical
13. If the rock falls off of the cliff, it gains energy called _______________ energy.
a. potential
b. kinetic
c. chemical
d. solar
e. electrical
14. Two marbles, one twice as heavy as the other, are dropped to the ground from the roof of a building.
Just before hitting the ground, the heavier marble has
a.
b.
c.
d.
e.
as much kinetic energy as the lighter one.
twice as much kinetic energy as the lighter one.
half as much kinetic energy as the lighter one.
four times as much kinetic energy as the lighter one.
impossible to determine
15. A woman runs up a flight of stairs. The gain in her gravitational potential energy is GPE. If she runs up
the stairs at half the speed, her gain in gravitational potential energy will be
a. (GPE)/4
d. 2(GPE)
b. (GPE)/2
e. 4(GPE)
c. (GPE)
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Math Problems: Conservation of Energy
16. A 90 kg leopard sits in a 4 m high tree and waits for some prey to pass underneath.
a. What kind of energy does the leopard have?
b. How much energy does the leopard have?
17. A 1500 kg Indy car races down a flat track at 100 m/s.
a. What kind of energy does the Indy car have?
b. How much energy does the Indy car have?
18. Jennifer is riding her bike at a constant speed down a flat road. She and the bike combined have a
kinetic energy of 625 Joules. Assuming the combined mass of Jennifer and the bike is 50 kg, how fast is
she going?
19. A 1-kg block starts from rest 1 m up a frictionless 30° ramp. On the horizontal surface is a 0.5 m rough
surface with a coefficient of kinetic friction of 0.3. After the rough stretch, the horizontal surface is
again frictionless and there is a spring with a spring constant 500 N/m. How far is the spring
compressed?
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20. A 200 kg gargoyle is perched on top of Notre Dame cathedral. He is 50 meters off the ground.
a. If it were to fall with no air resistance, how much kinetic energy would it have when it was just
about to hit the pavement underneath?
b. What will its speed be the moment before it hits the pavement?
21. A 60 kg gymnast on a trampoline leaves the trampline going 7 m/s.
a. How much gravitational potential energy will the gymnast have when they reach the highest
point?
b. How high off the trampoline will they be at the highest point?
22. A 20.0 kg cart on wheels on a horizontal surface has been pushed up against a wall into a spring with
spring constant of 244 N/m. The spring is compressed a distance of 0.100 m and starts from rest.
a. What will be the velocity of the cart when it leaves the spring?
b. Once it leaves the spring, it travels a distance until it comes to rest due to friction (µ k = 0.2).
What distance will it travel?
23. A 4400-kg roller coaster car starts with a velocity of 10.0 m/s at the top of a 36.5-m high track.
Determine the speed of the car at the top of a loop that is 10.8 m high if 500,000 J of energy is lost
along the way.
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