20 Points About Work

1. Work is done whenever there is a change or transfer of energy.

2. The law of conservation of energy states that energy can neither be created nor destroyed only converted from one form to another.

3. Some energy is always lost by conversion to heat and often sound energy.

4. In order for work to be done 3 conditions must be met:
1. A force must be exerted.
2. There must be displacement.
3. At least some of the force has to be in the direction of the displacement.

5. Formula to calculate work: W=F cosθ Δ d.

6. If the force is parallel to x or y axis θ = 0 and since cos θ =1 W = F Δ d.

7. Work is measure in Newton meters or Joules.

8. The joule is named after the British physicist James Prescott Joule.

9. Work is a scalar value even though it is the product of two vectors.

10. There is positive and negative work.

11. When force and displacement are in the same direction the work is positive.

12. If the force is the opposite to displacement, the work is negative.

13. Work can also be calculated graphically.

14. To calculate work graphically, find the area under a force displacement graph.

15. Graphs are usually used to calculate work done by changing force on an object.

16. If the force uniformly increases, then the work is equal to the area beneath the triangular force displacement graph.

17. In this case the formula for the area of a triangle ½ B x H can be used to calculate work.

18. Graphical calculations can be used to calculate the work of nonuniformly changing force.

19. However it is much more difficult in this case.

20. It is often done by counting the whole squares beneath the graph and estimating the pieces. This method is pretty accurate, but not one hundred percent.