Lesson 1: Work Done and Power

Question 1

What other unit can you write a Joule (J) as?

Answer 1

1J - 1Nm

Question 2

What is work done?

Answer 2

The energy transferred from one store to another when a force moves object through distance.

Question 3

How do you calculate work done?

Answer 3

Force x distance

Question 4

What is power?

Answer 4

• Power is the rate of energy transferred each second/ the rate at which work is done.
• Measured in W

Question 5

What is power measured in?

Answer 5

• Power is measured in Watts (W)

Question 6

What is the equation for power?

Answer 6

P = E/ t

Question 7

What is “work done” the same as?

Answer 7

• Work done is the same as energy transferred.

Question 8

Q - Which example has a higher power?
A sprinter running the 100 m in 10 s, or
A marathon runner completing their last 400 m in 50 seconds

Answer 8

• Sprinter speed: 100/10=10m/s
• Marathon speed: 400/ 50= 8m/s

Sprinter –> higher speed = higher power.

Question 9

What are the factors affecting power?

Answer 9

• The amount of energy transferred
• Time taken

Question 10

If a person’s force of gravity is 600N and they climb up stairs with a vertical height of 5m, how much energy has been transferred?

Answer 10

600Nx 5m = 3000J
IR: it must be the VERTICAL HEIGHT as the distance must in same direction as force

Question 11

What is a different unit for power other than W?

Answer 11

J/s
(Also written as: Js⁻¹)

Question 12

What are the 2 equations for power?

Answer 12

Power = work done/ time
Power = energy transferred/ time

Question 13

What are the 2 types of work?

Answer 13

• Mechanical work: force moving object.
• Electrical work: current transferring energy.

Question 14

What energy transfer is involved when a moving car brakes?

Answer 14

• Kinetic energy
• HEATING PATHWAY
• Thermal energy in tires as brakes rub against them.