1. Tue Jan 31 Today Review hw 5. 5 Read p293-295. (p280) 83,87,91
Tue Jan 31 Today Review hw 5.5 Read p (p280) 83,87,91 (p307-9) 56, 61,76,81,82 ch test next Tue. or Wed.!

2. The formula for kinetic energy is:
K=(mv2)/2
K=(mv)2/2
K=2mv2
K=(mg)/h
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3. The SI units for energy and work are:
Newtons
Watts
Joules
Amperes
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4. Kinetic energy is a ____ quantity
Tensor
Scalar
Vector
Negative
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5. The transfer of energy by mechanical means is called _______.
Heat
Machination
Work
Force
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6. Work is done when: A force acts through a distance.
A hot object touches a cold object.
A force acts perpendicular to a displacement
You sleep on the job.
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7. Energy stored in an object that has been lifted in a gravitational field is called:
Elastic potential energy
Gravitational potential energy
Chemical potential energy.
Thermal energy.
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8. If an object’s speed doubles its kinetic energy:
Quadruples
Doubles
Is cut in half.
Doesn’t change
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9. The kinetic energy of a 4.0 kg object moving at 3.0 m/s is:

10. How much work is done if you push a 5
How much work is done if you push a 5.0 kg box 12 meters across the floor while applying a 10.0 N force?
50 J
60 J
120 J
600 J
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11. How much work do you do if you lift a 6.0 kg object 50 cm up?
None
3.0 J
30 J
3.0 kJ
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12. _____ describes how quickly energy is transferred.
Kinetic energy
Velocity
Power
Pressure
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13. The SI units of power are:
Joules
Teslas
Pascals
Watts
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14. A Watt is equal to
N m
J s
N/m2
J/s
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15. I have 1.2 kW microwave. How much electrical energy is converted if I heat something on high for 30 seconds?
40 J
400 J
600 J
36 kJ
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16. If the power output of a motor is 65 W, how long does it take to do 195 J of work?
1.95 seconds
3.0 seconds
260 seconds
3.5 hours
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17. ________ is where we decide to set gravitational potential energy to zero.
The null zone
Outer space
The reference level
On top of spaghetti
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18. Which of the following is a conservative force?
Friction
Thrust
Gravity
Air resistance
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19. A 4. 0 kg object is moving has 72 J of kinetic energy when it is 3
A 4.0 kg object is moving has 72 J of kinetic energy when it is 3.0 m above the reference level. Its speed is
2.0 m/s
5.0 m/s
6.0 m/s
192 m/s
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20. A 4. 0 kg object has 72 J of kinetic energy when it is 3
A 4.0 kg object has 72 J of kinetic energy when it is 3.0 m above the reference level. Its total mechanical energy is
0.0 J
72 J
120 J
192 J
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21. A 4. 0 kg object has 72 J of kinetic energy when it is 3
A 4.0 kg object has 72 J of kinetic energy when it is 3.0 m above the reference level. Once it falls down to the reference level it will have a kinetic energy of
72 J
120 J
192 J
0.0 J
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22. Simple machines can NOT
Multiply the force that is exerted
Multiply the work that is done
Change the direction a force is exerted
Change the speed
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23. The mechanical advantage of a simple machine describes
How much the machine multiplies the work you do
How much the distance is multiplied
How much the force is multiplied
How much the power is multiplied
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24. The efficiency of a machine describes:
The ratio of the output work to the input work
The ratio of the output force to the input force
The ratio of the output distance to the input distance
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25. An input of 8.0 kJ of work is is provided to a machine that exerts a 2.0 kN force through a distance of 3.0 meters. What is the efficiency?
25%
37.5 %
75%
133%
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26. A pulley is used to raise a 2. 0 kg object 50 cm off of the table
A pulley is used to raise a 2.0 kg object 50 cm off of the table. The work done BY the machine is:
1.0 kJ
100 J
10.0 J
1.0 J
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27. A pulley is used to raise a 2. 0 kg object 50 cm off of the table
A pulley is used to raise a 2.0 kg object 50 cm off of the table. The person pulling the string exerts a force of 8.0 N through a distance of 2.0 m. How much work is done by the person?
1.0 J
10.0 J
4.0 J
16 J
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28. A pulley is used to raise a 2. 0 kg object 50 cm off of the table
A pulley is used to raise a 2.0 kg object 50 cm off of the table. The person pulling the string exerts a force of 8.0 N through a distance of 2.0 m. The mechanical advantage of the machine is
4.0
2.5
2.0
0.50
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29. A pulley is used to raise a 2. 0 kg object 50 cm off of the table
A pulley is used to raise a 2.0 kg object 50 cm off of the table. The person pulling the string exerts a force of 8.0 N through a distance of 2.0 m. The efficiency of the machine is
31%
63%
100%
160%
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30. If a machine has a mechanical advantage of 5
If a machine has a mechanical advantage of 5.0 how much force must you exert to lift a 60 kg object?
60 N
120 N
300 N
3.0 kN
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31. A pulley is used to raise a 2. 0 kg object 50 cm off of the table
A pulley is used to raise a 2.0 kg object 50 cm off of the table. The person pulling the string moves their hand 2.0 m. What is the IMA of the machine?
4.0
2.5
0.25
10.0
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