Answers25-26 CHEMISTRY IN THE EARTH SYSTEM S1Conservation of Energy

Conservation of Energy Answers

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1
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A box is released from rest and slides down a ramp in a closed system. Even though the box speeds up, its kinetic energy at the bottom of the ramp is less than the potential energy that it had at the top of the ramp.

A
In a closed system, kinetic energy is always less than potential energy.
B
Some potential energy was converted into thermal energy due to friction.
C
The acceleration due to gravity became smaller as the box slid down the ramp.
D
In a closed system, total energy is constantly being lost to outside objects.
2
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What does the law of conservation of energy state about energy in a closed system?

A
Energy cannot be created or destroyed.
B
Energy can be created but not destroyed.
C
Energy can be destroyed but not created.
D
Energy can be either destroyed or created.
4

What is the potential energy of a spring that is compressed 0.65 m by a 25 kg block if the spring constant is 95 N/m?

A
1.6 J
B
7.9 J
C
15 J
D
20 J
5

Irving, a cat, has a favorite toy that is made up of a squeaky ball at the end of a string. The toy makes up a closed system. Irving’s owner dangles the toy so that the ball swings down and then swings back up again.

A
As the ball moves upward, both kinetic and potential energy decrease.
B
As the ball moves downward, both kinetic and potential energy increase.
C
As the ball moves upward, kinetic energy decreases and potential energy increases.
D
As the ball moves downward, kinetic energy decreases and potential energy increases.
6

A 440 kg roller coaster car is going 26 m/s when it reaches the lowest point on the track. If the car started from rest at the top of a hill, how much higher was that point on the track than the lowest point? (Use g = 9.80 m/s2, and ignore friction.)

A
17 m
B
23 m
C
34 m
D
69 m
7

Disregarding air resistance, what is the speed of a ball dropped from 12 feet just before it hits the ground? (Use 1 ft = 0.30 m, and use g = 9.8 m/s2.)

A
2.4 m/s
B
8.4 m/s
C
10.8 m/s
D
15.3 m/s
8

Which equation represents the law of conservation of energy in a closed system?

A
KEi + PEi = KEf + PEf
B
PEi + PEf = KEi + KEf
C
KEi – KEf = PEi – PEf
D
KEi – PEf = PEi – KEf
9

A famous motorcycle company has just built its first electric model. Like all vehicles, the purpose of the motorcycle is to put out kinetic energy.

Question illustration
A
50 J
B
200 J
C
400 J
D
800 J
10

When an object is not in motion, it can still have a form of energy. What form of energy does an object have due to its distance from Earth?

A
kinetic energy
B
thermal energy
C
gravitational potential energy
D
electrical potential energy

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