Work

• Work is done on an object when the object moves in the same direction in which the force is exerted.

• If no motion occurs then there will be no work.

• Did you do work with your book bag on your back walking to class?

Calculating Work

• Work depends on two things:

1. Force

2. Distance

• Which would require more work:

1. Lifting a 50N potted plant .5 m off the ground to a table or a 100N potted plant the same distance.

Calculating Work

• We can find the work it takes to move objects with the following equation.

W= Force (F) x Distance (d)

• The following unit is used for work:

• Joule (J)

Now, find how much work it would take to move each of the plotted plants.

Calculating Work

How much work would it take to move a 250 N car a distance of 5m?

How much work would it take to lift a 63 N book a distance of 3m?

Practice Problems

1. Calculate the work done on a wagon if you push it 35m with a force of 53N.

2. Calculate how much force you would need to pull a wagon if you applied 65 J of work and pulled a distance of 25m.

3. Would you be doing work to a box if you carried it to a moving truck? Explain.