Download presentation

Presentation is loading. Please wait.

Published byHolly Miner Modified over 2 years ago

1
**Work and Power 1. Describe the conditions that must exist**

for a force to do work on an object. 2. Calculate the work done on an object. 3. Describe and calculate power.

2
**What is Work? Work is the product of force and distance.**

Work requires motion. If there is no movement then no work is done. The force must act in the same direction as the object moves. Any part of a force that does not act in the direction of motion does no work on an object.

3
Calculating Work Work = Force x Distance

4
Units of Work The Joule (J) is the SI unit of work. It is the work of moving an object with the force of 1 Newton to a distance of 1 meter.

5
**Practice using the Work Formula**

A weight lifter lifts a 1600 N barbell over his head 2.0 meters high. W = F x D W = 1600 N x 2.0 m W = 3200 J

6
What is Power Power is the rate of doing work. Doing work at a faster rate requires more power. To increase power: 1. increase the amount of work done in a given time 2. do a give amount of work in less time.

7
Calculating Power Power = Work / Time

8
Units of Power The SI unit of power is the watt (W), which is equal to one joule per second.

9
How much work does a 25-newton force do to lift a potted plant from the floor to a shelf 1.5 meters high? 52 J 48 J 24 J 38 J 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32

10
You lift a large bag of flour from the floor to a 1-meter-high counter, doing 100 joules of work in 2 seconds. How much power do you use to lift the bag of flour? 50 W 52 W 48 W 42 W 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32

11
**In which of the following cases is work done on an object?**

Pushing against a locked door. Suspending a heavy weight with a strong chain. Pulling a trailer up a hill. Carrying a box down a corridor. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32

Similar presentations

© 2017 SlidePlayer.com Inc.

All rights reserved.

Ads by Google