1. Chapter 7: Work (Ewen et al. 2005)
Work and Energy
Objectives:
Distinguish the common and technical definitions of work.
Solve work problems.

2. What is work?
Common definition is different from the scientific definition.
The technical definition of work requires that work must be done by one object on another object.
Work is done when a force acts through a distance.
Work is the product of the force in the direction of the motion and the displacement.

3. When the force is in the same direction as the displacement of the object
When the force is at an angel relative to direction of displacement

4. Example 1
Find the amount of work done by a worker lifting 225 N of bricks to a height of 1.75 m.

5. Example 2
A worker pushes a 350 lb cart a distance of 30 ft by exerting a constant force of 40 lb. How much work does this person do?

6. Example 3
A person pulls a sled along a level fround a distance of 15.0 m by exerting a constant force of 215 N at an angle of 30.0o with the ground. How much work is done?

7. Example 4
Juan and Sonja use a push mower to mow a lawn. Juan, who is taller, pushes at a constant force of 33.1 N on the handle at an angle of with the ground. Sonja, who is shorter, pushes at a constant force of 23.2 N on the handle at an angle of with the ground/. Assume they each push the mower 3000 m. Who does more work and by how much?