1. Work

2. Definition
(p199) Energy is defined as the ability to do work
In Physics, we must define work simply as the product of force and displacement.
Work = Force × displacement
W = F × d

3. When is work done? When we do work, it is done on an object.
If an object does not move through some displacement, then no work is done on that object.
In the same way, if there is no force acting on the object, there is no work.
Symbol: W
Units: Nm which is called a Joule

4. Special notes: part 1
(p200) When an object is lifted at constant velocity, work is done against gravity. In this case W = Fd or W = magh
The force used in the formula, W = Fd, is the applied force rather than the ΣF (net force).
Although work is a product of two vector quantities, it is a scalar quantity.

5. Special notes: continued
When the force is not in the same direction as the displacement, we must use the component of the force that is in the direction of the displacement. (See example 4 p 201)
Work can be negative. If the force on the object is in the opposite direction to the motion, the work done on the object is negative.

6. See example problems p 201
d = 0 and since W = Fd, W = 0
4. W = Fd or W = Fxdx:
5. Note this question requires 3 steps/formulae

7. Work Graphs
(add to top of p 201) The area under a F/d graph is work: