Work, Power, And Energy Question Preview (ID: 53677)

Test Review.

A force acting on an object does no work if
a) a machine is used to move the object
b) the force is greater than the force of friction
c) the force is not in the direction of the object's motion
d) the object accelerates.

If you exert a force of 10.0 N to lift a box a distance of 0.75 m how much work do you do?
a) 0.075 J
b) 10.75 J
c) 7.5 J
d) 75 J

If you perform 30 J of work lifting a 20 N box from the floor to a shelf how high is the shelf?
a) 0.5 m
b) 2 m
c) 0.6 m
d) 1.5 m

The standard (SI) unit of power is
a) Watt
b) Joule
c) Horsepower
d) N

Why does friction decrease the efficiency of a machine ?
a) It reduced the speed of a machine
b) It increases the force of a machine
c) It increases the input energy of a machine
d) It converts some input energy into thermal energy

Reducing friction in a machine
a) decreases its actual mechanical advantage
b) Increases its efficiency
c) decreases the work output
d) increases its ideal mechanical advantage

An inclined plane reduces the effort force by
a) increasing the distance through which the force is applied
b) reducing the effort distance
c) increasing the work
d) reducing the work

A machine does work, it can do all of the following except
a) change the direction of a force
b) change the size of the force needed
c) change the distance the force is applied
d) change the amount of work done.

As the temperature of an object rises so does the
a) kinetic energy of the object
b) potential energy of the object
c) thermal energy of the object
d) Both 1 and 3

Which of the following increases when an object becomes warmer
a) Chemical energy
b) thermal energy
c) nuclear energy
d) elastic potential

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