Work & Energy Theorem Notes 1-35

In which of the following cases is no work done by the applied force?

• A softball player catches a ball in her glove.

• A home owner is applying his force to move his lawnmower from rest.

• A driver applies the brakes to slow his car.

• A student holds his textbook in front of him and does not move.

A 36.0 N force is applied to an object that moves 11.0 m in the same direction as the applied force on a frictionless surface. How much work is done on the object by the force? (Round to 3 sig figs, no untis)

A 36.0 N force is applied to an object that moves 11.0 m in the opposite direction of the applied force on a frictionless surface. How much work is done on the object by the force? (Round to 3 sig figs, no units)

A 36 N force is applied to an object that remains stationary. How much work is done on the object by the applied force? Round to "1 sig fig", no unit

After being pushed with a significant force, a 2.0 kg block slides 4.5 m to the right on a frictionless table with a constant velocity of 5.0 m/s. What is the net work on the block? Round to "1 sig fig", no units

A book is held at a height of 2.0 m for 20 s by a librarian. How much work is done on the book by the librarian? Round to "1 sig fig" no units!

How much force must be applied to an object such that it gains 100.0 J over a displacement of 20.0 m? Round to 1 sig fig, no units)

Over what displacement must a 400.0 N force be applied to an object such that it gains 1600 J of energy?

1. A vacuum cleaner is moved from the ground floor to the

second floor of an apartment building. In which of the

following cases is the most work done by the person

moving the vacuum? (Don't consider mechanical advantage or Joules/second)

• The vacuum cleaner is pushed up an incline set

  over the stairs.

• The person carries the cleaner up the stairs

  in his arms

• The cleaner brings the cleaner to the third floor, by

  mistake, then back to the second floor.

• The work is the same in each case.