1. Section B1.4
Work and Energy

2. Types of Energy
Mechanical Energy – is the energy which is possessed by an object due to its motion or due to its position; mechanical energy can either be kinetic energy or potential energy
Kinetic Energy – the energy of motion
Potential Energy – stored energy; energy having the potential for doing work

3. Work An object which possesses mechanical energy is able to do work.
In fact, mechanical energy is often defined as the ability to do work.
Work – is the transfer of mechanical energy from one object to another
For example, if you stretch or compress a spring, you do work on the spring and transfer energy to the spring.

4. Work
The amount of work done on an object can be calculated by multiplying the force exerted on the object by the distance which the object moves.
Force – push or pull on an object
W=F x Δd

5. Work W=F x Δd Where: W is the work done in Joules (J)
F is the force in Newtons (N)
Δd is the distance in meters (m)

6. _____________________________________________
Work
***In order for work to be done the direction of the force and the direction of the motion must be parallel, or along the same line.
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7. Example Problem #1
Example: You exert a force of 25 N on your textbook while lifting it a height of 1.4 m to put it on a shelf. How much work did you do on your textbook?

8. Example Problem #2
A weightlifter lifts a barbell a vertical distance of 2.40m. If the average force required to lift the barbell is 2.00 x 103N, how much work is done by the weightlifter?