Work Power And Efficiency

Question 1

What is work measured in?

Answer 1

Joules

Question 2

What does the amount of work done depend on?

Answer 2

Size of the force
The distance the force makes the body move

Question 3

What is the rate at which energy is transferred called?

Answer 3

Power

Question 4

What is the unit for power?

Answer 4

Watts

Question 5

What is efficiency?

Answer 5

How good a device is at transferring energy usefully

Question 6

How does a kettle use energy usefully and how is it wasted?

Answer 6

U:Energy that heats the water
W:Thermal energy heats the kettle
W:Infrared radiation lost to the surroundings

Question 7

How does a hair dryer use energy usefully and how is it wasted?

Answer 7

U:Thermal energy heating the air
U:Kinetic energy of the fan blows the air
W:Sound radiation
W:Thermal energy lost to surroundings

Question 8

How does a light bulb use energy usefully and how is it wasted?

Answer 8

U:Light radiation given out by hot filament
W:Infared and thermal lost to surroundings

Question 9

How does a Tv use energy usefully and how does it waste it?

Answer 9

U:Light radiation allows image to be seen
U:Sound radiation allows audio to be heard
W:Thernal energy heating the TV set