P1

Question 1

What are the 8 different energy stores

Answer 1

Thermal, kinetic, gravitational potential, elastic potential, chemical, magentic, electrostatic, nuclear

Question 2

What are the 4 ways energy is transfered

Answer 2

Mechanically, electrically, heating or radiation

Question 3

What is a system

Answer 3

A single object or a group of objects

Question 4

What happens when a system is changed

Answer 4

Energy is transfered. Into or away from the system

Question 5

What are closed systems

Answer 5

Systems where neither matter nor energy can enter of leave the system

Question 6

Whats another way of saying energy transfered

Answer 6

Work done

Question 7

Example of how energy can be transfered through heat

Answer 7

Boiling water in a kettle . Water is system and energy id transfered to the water by heating into the waters thermal energy store.

Question 8

Example of a frictional cause of transfer of energy

Answer 8

Friction between car’s brake and its wheels does the work as it slows down. It causes an energy transfer from wheel’s kinetic energy store to the thermal energy store of the surroundings

Question 9

What is the conservation of energy principle

Answer 9

Energy can be transfered usefully, stored or dissipated, but can never be created or destroyed

Question 10

What is dissipated energy

Answer 10

Wasted energy because the energy is being store in an unuseful way

Question 11

Example of dissipated energy

Answer 11

A mobile phone is a system, when you use your phone, energy is usefully transfered from the chemical energy store of the battery in the phone. But some of the energy is dissipated and this dissipated energy is transfered to the thermal energy store of the phone

Question 12

What is power in physics

Answer 12

Rate of energy transfered or rate of doing work

Question 13

What is power measured in

Answer 13

Watts

Question 14

Equations to calculate power

Answer 14

Power = energy transfered/time
Power = work done/time

Question 15

What does lifting an object in a gravitational field require and what does this cause

Answer 15

Work and this causes a transfer in energy to the gravitational potential energy store of the raised object. The higher the object is lifted, the most energy is transfered to this store

Question 16

Gpe

Answer 16

Gravitational potential energy store

Question 17

What does the amount of energy in a gpe store depend on

Answer 17

Mass height and strength of gravitational field strength

Question 18

Equation for change in energy in an objects gravitational potential energy store

Answer 18

E=mgh - mass x gravitational field strength x height
E= gpe (J)
M=mass kg
G= gravitational field strenfth (N/kg)
H=heght (m)

Question 19

Elastic potential energy equation

Answer 19

E=1/2 Ke^2
E= elastic potential energy (J)
K= spring constant (N/m)
E= entension (m)^2

Question 20

How do you know if something has a kinetic energy store

Answer 20

Anything that is moving has energy in it’s kinetic energy store

Question 21

When does energy travel to and from the kinetic energy store

Answer 21

When an object speeds up, energy is transfered to this store. When an object slows down, energy is transfered away from this store

Question 22

What does energy in the kinetic energy store depend on

Answer 22

The objects mass and speed. The greater mass, the faster the object travels, the more energy there will be in its kinetic energy store

Question 23

Equation for kinetic energy

Answer 23

E= 1/2mv^2
E= kinetic energy (J)
M= mass (kg)
V = speed (m/s)^2

Question 24

Why are useful devices useful

Answer 24

Because they can transfer energy from one store to another

Question 25

How can you improve the effiency of energy transfers

Answer 25

Insulating objects, lubricating them or making them more streamlined

Question 26

Energy effiency equation

Answer 26

Useful power output/total power output

Question 27

Equation for useful energy transfer

Answer 27

Useful output energy transfer / total input energy transfer

Question 28

What is one thing that is 100% energy efficient and why

Answer 28

Electric heaters because in the electrostatic energy store is transfered to ‘useful’ thermal energy stores

Question 29

Ultimetely, all energy ends up transfered to

Answer 29

Thermal energy stores

Question 30

Energy is transfered between stores electrically by…

Answer 30

Electrical appliances

Question 31

Why does moving charge transfers energy

Answer 31

Because it does work against the resistance of the circuit

Question 32

What are electical appliances designed to do

Answer 32

Transfer energy to componants in the circuit when a current flows

Question 33

What does it mean if the current is higher

Answer 33

The more energy is transfered to the thermal energy stores of the componants

Question 34

What is the power of an applience

Answer 34

The energy that it transfers per second. So the more energy it transfers in a given time, the higher it’s power

Question 35

Equation for energy transfered

Answer 35

Energy transfered (J) = power (W) x Time (S)

Question 36

What are appliances often given

Answer 36

Power rating -

Question 37

What does a power rating tell you

Answer 37

The maximum amount of energy transfered between stores per second when the appliance is in hse

Question 38

What does a lower power rating mean

Answer 38

Less power rating means less electricity an appliance uses in a given time and so the cheaper it is to run