1. Work and Energy Definition of Work Kinetic Energy Potential Energy
Conservation of Mechanical Energy
Power
Efficiency

2. The product of Force and distance moved In the direction of the force
What is work?
The product of
Force and distance moved
In the direction of the force

3. In the direction of the force
Force and displacement must be in the same dimension
Parallel or antiparallel
If parallel, work done is positive
If antiparallel, work done is negative
If force is perpendicular to displacement, work done is zero.

4. Negative work is also referred to as Work done against the antiparallel force

5. F s
Work = F x s
Positive work
Units for Work: Nm or Joule, J

6. Weight
Work done by
Weight
Zero
Normal
Friction
Negative
Tension
Friction
Normal Force

7. No work for
Gravity and
Normal force s
Work = (F cos 30) x s

8. Examples

9. How do you calculate for total work?

10. To calculate for total work
Sum of all of the work done by each force Or
Net force x displacement

11. Points on Total Work If net force is zero, total work is also zero.
If net work is not zero, then the body is accelerating.
Equation

12. The stored ability to do work
What is energy?
The stored ability to
do work

13. Kinetic Energy of an object
Stored ability to do work because of its motion.
Work –Energy Theorem

14. Examples

15. The work done by gravity

16. Second case

17. (Gravitational) Potential Energy of an object
Stored ability to do work as a result of it position.
Conservation of Mechanical Energy

18. Examples

19. The rate of doing work Work done per unit time Equation Units
Power
The rate of doing work
Work done per unit time
Equation
Units

20. Power and Quality of work
are not the same.

21. Power output per power input
Efficiency
Power output per power input

22. Example
A simple pendulum, consisting of a mass m, is attached to the end of a 1.5 m length of string. If the mass is held out horizontally, which makes a 60°angle with the vertical, and then released from rest, what is its speed at the bottom?

23. Example
If the kg roller coaster leaves Point Q from rest, how fast is it traveling at Point R?

24. Example
If the 1000-kg roller coaster leaves Point Q from rest, what is its speed at Point S?

25. Past Paper Example

26. Past Paper Example

27. Past Paper Example