Chapter 10

Question 1

Energy

Answer 1

Ability to do work

Question 2

Work

Answer 2

Work is the product of the magnitude of the force applied to an object and the distance the object moves along the direction of the applied force.

W = F x D

Question 3

When is work done negative?

Answer 3

When force and motion are in opposite directions

Question 4

Is work a scaler?

Answer 4

Yes it is the magnitude of force and the distance

Question 5

Unit for work?

Answer 5

joule (J)
1 joule is the amount of work done when a force of 1 N moves an object a distance of 1m (or 2 Newtons moves it 1/2 m).

Question 6

If you carry a book across a room do you do any work?

Answer 6

No, because force is perpendicular to the motion

Question 7

What are two important things to remember?

Answer 7

1. When several forces are involved, work is done by each force. work is not calculated using net force.
2. Walking up a hill or going up stairs - other than starting out, work is only done to go up, not to move forward.

Question 8

Power

Answer 8

Rate of doing work - rate at which energy is transferred
P = W/t or P = ΔE/t

Question 9

Is power a scalar

Answer 9

Yes

Question 10

Unit for Power

Answer 10

J/s = W (watt)
Since 1 watt is a very small amount of power, it is often measured in kilowatts - kW - 1 kW = 1000W