Work, Power and Energy

Which of the following illustrations shows that there is no work done?

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When using a machine, what would you call the work done by the machine?

• work in

• work out

• distance in

• distance out

• efficiency

The efficiency of a ramp is 86.7%. If the ramp does 65 J of work, how much work have you done?

• more than the work done by the ramp

• less than the work done by the ramp

• the same amount of work done by the ramp

Which of the following situations shows No Work is done?

• a boy pushing his toy cart

• an audience sitting on the bench

• a janitor pushing a chair to the corner

• a bride throwing her bouquet of flowers

Is there work done by pushing a wall for three hours?

• Yes, because a force is exerted on the wall.

• Yes, because you push the wall for three hours.

• None, because the wall is too heavy to push.

• None, because the wall did not change its position.

When is work done on an object?

• when the force is zero

• when the displacement is zero

• when the displacement is not zero

• when force and displacement are perpendicular

Two equal mass marbles are at the top of a ramp. One marble falls to the ground off the back while the other rolls down the ramp. What is true about the marbles when they reach the ground?

• The marble that rolled down the ramp is moving faster than the marble that fell.

• The marble that fell down the back of the ramp is moving faster than the marble that rolled.

• The marble that rolled down the ramp is not moving when it reaches the ground.

• The two marbles are moving with the same speed.

Dan climbs a flight of stairs in 1.5 minutes. if he weighs 450 N and the stairs is 10 m from the ground, how much power will he develop?

• 50 W

• 200 W

• 150 W

• 25 W

If there is no friction on this track, at which point would the coaster have the most kinetic energy?

• A

• B

• C

• D

How much work is done by a student who lifts a 5-kg box to a vertical height of 1.5 m?

• 74 J

• 75 J

• 78 J

• 80 J