Work Power and Machines Work n How the

Work, Power, and Machines

Work n How the world works…. The way of the Work

Work …. Can you work overtime Dude! I need a raise

What is work? n In science, the word work has a different meaning than you may be familiar with. 4

Work The product of the force applied to an object and the distance through which that force is applied. n. Work = force x distance n. W = Fd

Work n. Work is measured in: n. N m n. Joules (J)

To measure work, you must know the force (N) and the distance (m) The unit for work is the Joule We mo wor ney k t to o ma bu y “ ke jou les ”.

n *Work is only done when the force is in the same direction as the object moving*

Energy can produce a Force which can move something to do Work

Work or Not?

Is work being done or not? § § § Mowing the lawn Weight-lifting Moving furniture up a flight of stairs Pushing against a locked door Swinging a golf club § YES YES § NO § YES § §

Work Example n. A crane uses an average force of 5200 N to lift a girder 25 m. How much work does the crane do?

Work Example n. Work = Fd n. Work = (5200 N)(25 m) n. Work = 130000 N m = 130000 J

History of Work Before engines and motors were invented, people had to do things like lifting or pushing heavy loads by hand. Using an animal could help, but what they really needed were some clever ways to either make work easier or faster. 14

Work= Force x Distance W Work- Joule (J) Force-Newton (N) Distance-Meter (m) F D

1. If you lift a bag that weighs 15 N a distance of 2 m, how much work have you done? Work- ? Force- 15 N Distance. W= Fd 2 m 15 N x 2 m = 30 J 15 N 2 m

2. A 950 N skydiver jumps from a plane that is 3000 m high. What is the total work performed on the skydiver? Work- ? Force- 950 N Distance- 3000 m 950 N 2, 850, 000 J 3000 m

3. A bulldozer performs 80, 000 J of work on a load of dirt that is moved 16 m. What is the force of the dirt? Work- 80, 000 J Force- ? Distance- 16 m F=W/d 5000 N 16 m

4. How much work is done by a person who uses a force of 27. 5 N to move a shopping cart 12. 3 m? Work- ? Force- 27. 5 N Distance- 12. 3 m 338. 25 J Or 338. 3 J 27. 5 N 12. 3 m

5. A force of 10, 000 N is used to push on a stationary wall. How much work is done? Work- ? Force- 10, 000 N Distance- 0 m W= Fd 0 J 10, 000 N 0 m

Do Now 1. How much work does a tiger do while moving a ball, in a circus, 5 meters with a pulling force of 11 N? 55 J Work- ? Force- 11 N Distance- 5 m 11 N 5 m

DO NOW 2. Joe balances a stationary coin on the tip of his finger 20 cm from the top of the table. Gravity is pulling with a force of 5. 67 g. How much work is Joe doing? Work- ? 0 J Force- (mass 5. 67 g) Distance- 0 m . 05 N 0 m