CHANGES IN ENERGY STORES

Question 1

what happens when energy is transferred?

Answer 1

the energy is then stored in one of the object’s energy stores

Question 2

GEEKS LUNCH

Answer 2

gravitational potential energy stores
electrical energy stores
elastic potential energy stores
kinetic energy stores
sound energy transfer 

light energy transfer
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nuclear energy stores
chemical energy stores
heat (thermal) energy stores

Question 3

how is energy transferred?

Answer 3

mechanically (by a force doing work) or electrically (work done by moving charges) by heating/radiation

Question 4

what is a system?

Answer 4

a single object or a group of objects

Question 5

what happens when a system changes?

Answer 5

energy is then transferred into or away from the system either between different objects in the system or between different types of energy stores

Question 6

what is a closed system?

Answer 6

a system where neither matter nor energy can enter or leave

Question 7

what is the net change in a closed system?

Answer 7

it’s always 0

Question 8

how is energy transferred in a kettle?

Answer 8

water is the system and energy is transferred to the water by heating, into the water’s thermal energy store

Question 9

describe the system between the water and the kettle’s heating element?

Answer 9

the kettle’s heating element and the water are a 2-object system

• the energy is transferred electrically to the thermal energy store of the kettle’s heating element
• which then transfers the energy by heating to the water’s thermal energy store

Question 10

define work done?

Answer 10

when energy is transferred

Question 11

when can work be done?

Answer 11

when a current flows or by a force of a moving an object

Question 12

describe the work done when a ball is thrown upwards by a person?

Answer 12

energy is transferred from the chemical energy store of the person’s arm to the kinetic energy store of the ball and arm

Question 13

describe the work done when a ball drops?

Answer 13

it accelerates due to gravity

-energy is transferred from the ball’s GPE store to its kinetic energy store

Question 14

describe the work done when a car brakes?

Answer 14

frictional forces causes a transfer of energy from the wheel’s kinetic energy stores to the thermal energy store of the surroundings

Question 15

describe the collision between a car and a stationary object?

Answer 15

energy is transferred from the car’s kinetic energy store to other energy stores:

• the elastic potential and thermal energy stores of the object and car body
• some energy might also be transferred away by sound waves

Question 16

chemical energy stores

Answer 16

fuels, foods, chemicals found in batteries

energy is transferred during chemical reactions

Question 17

kinetic energy stores

Answer 17

the energy an object has because it’s moving

Question 18

gravitational potential energy stores

Answer 18

the energy stored in an object because of its position

Question 19

elastic potential energy store

Answer 19

the energy stored in a springy object when you stretch or squash it

Question 20

thermal energy stores

Answer 20

the energy a substance has because of its temperature

Question 21

what happens when energy is transferred in a torch?

Answer 21

the torch’s battery pushes a current through the bulb

making the torch emit light and also get hot

Question 22

chemical energy store in the battery - electric current in the wires-

Answer 22

energy transferred to the surroundings - light waves / increases in the thermal energy store of the surroundings

Question 23

what happens when an object hits the floor?

Answer 23

all of the energy in its kinetic energy store is transferred by heating to the thermal energy store of the object and the floor

• there are sound waves moving away from the point of impact
• it’s a much smaller amount than the energy transferred by heating

Question 24

GPE store - kinetic energy store -

Answer 24

energy transfer to the surroundings - increase in the thermal energy store of the surroundings/ sound waves

Question 25

what happens when an object falls ?

Answer 25

it speeds up as it falls

the force of gravity acting on the object causes energy to be transferred from its GPE store to its kinetic energy store

Question 26

when a ball rolls hits a wall

Answer 26

the system is the moving ball

-when it hits the wall some kinetic energy is transferred as sound

Question 27

when a vehicle slows down

Answer 27

the system is the vehicle moving

-when it slows down the kinetic energy transfers to thermal due to friction between wheels and brakes