physics 1

Question 1

name the 5 energy stores

Answer 1

• kinetic
• gravitational potentiak
• elastic potential
• thermal
• chemical

Question 2

name the four 4 ways energy can be transferred

Answer 2

• heating
• waves
• electric current
• mechanically(by forces)

Question 3

what is a system

Answer 3

an object or group of objects

Question 4

what is a closed system

Answer 4

a system where no energy can be transferred to or from the surroundings

( total energy stays the same)

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Question 5

what is work done

Answer 5

energy transferred when a force moves an object

Question 5

what is the unit for energy

Answer 5

joules ( J )

Question 6

describe an energy transfer when a moving car slows down

Answer 6

1. energy is transferred mechanically from the kinetic store of the car
2. energy then transfers to the thermal store of its breaks
3. some energy is dissipated to the thermal store of the surroundings

Question 7

what is one joule of work done ?

Answer 7

the work done of a forces 1N causes an object to move 1m in the direction of the force

Question 8

describe an energy transfer when an electric kettle is used to heat water

Answer 8

1. the electric current in a kettle transfers energy to the heating element’s thermal store
2. energy is then transferred by heating to the thermal store of the water

Question 9

Describe the energy transfer when a ball is fired
using an elastic band.

Answer 9

1. energy is transferred mechanically from the elastic store of the elastic band
2. energy is then transferred to the kinetic store of the band
3. some energy is dissipated to the thermal store of the surroundings

Question 10

Describe the energy transfer when a battery
powered toy car is used.

Answer 10

1. energy is transferred electrically from the chemical store of the battery to the kinetic store of the toy car
2. some energy is dissipated to the thermal store of the surroundings

Question 11

Describe the energy transfer when a falling apple
hits the ground.

Answer 11

1. energy is transferred from the kinetic store of the apple
2. dissipated to the thermal store of the surroundings by sound waves

Question 12

Name the unit that represents one joule
transferred per second.

Answer 12

watt (W)

Question 13

A motor is 30% efficient. What does that mean?

Answer 13

30% of the energy is usefully transferred and 70% is
dissipated