Physics paper 1 (upto efficiency in p1)

done p1

List the 8 energy stores

thermal

kinetic

gravitational potential

elastic potential

chemical

magnetic

electrostatic

nuclear

4 ways energy can be transferred

mechanically

electrically

heating

radiation

whats a closed system

A closed system is a physical system that does not allow energy to enter or exit, although energy in the form of heat or work can still be transferred within it

describe a system of your choices energy transfer

any thing that can change energy from one store to another, such as a heating system transferring thermal energy to a room or a battery transferring chemical energy to electrical energy.

What is work done the same as

energy transfer

work is done against a ____________

resistance

give an example of work being done against a resistance

e.g. throwing a ball, resistance is air resistance, which opposes the motion.

energy lost from a store = energy _____ in ______ store

gained, another

the faster something is moving the _____ ______ energy

more, kinetic

a greater mass means an object requires ______ kinetic energy

more

the _____ an object is lifted the more _________ __________ energy

higher, gravitational

what is Specific heat capacity?

The amount of energy need to raise the temperature of 1kg of a substance by 1degrees celcius

SHC equation

△E=mc△θ

What is the conservation of energy principle?

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

what is wasted energy

energy is being stored in a way that is not useful (eg. heat from a lamp- wastes energy stored as thermal energy.

Describe an example of an energy transfer in a closed system

What is the net change in energy in a closed system?

0

power is measured in what?

watts W

What are watts

the joules of energy transferred per second

A powerful machine can transfer a lot of ______ in a _____ space of ______

energy, short, time

Conduction

Is the process where vibrating particles transfer energy to neighbouring particles

Conduction occurs where?

Mainly in solids

How do vibrating particles transfer energy?

Through the particles’ kinetic energy stores

How will Higher thermal conductivity affect the speed of energy transfer?

quicker

convection

where energetic particles move away from hotter to cooler regions

where does convection occur

liquids and gases

Describe the events of conduction

1. Energy transferred to thermal store of object by heating

2. heated= vibration

3. particles collide

4. energy transferred through kinetic stores

5. continues to other side of object

6. transferred to energy store of surroundings

Describe the events of convection

1. Energy transferred by heating to thermal store of substance

2. Heating= Particles move faster= Space in between particles increases= density decreases

3. warmer and less dense region rises above cool dense regions

4. energetic particles move from hot to cold regions

What density are materials better at conducting?

High

Lubrication ______ frictional forces

reduces

Frictional forces acting against a ______ object causes some ________ in the system to be ___________

moving, energy, dissipated

What does insulation do?

Reduce the rate of energy transfer by heating

How can i prevent energy loss through heating in a house?

• thick walls made by low thermal conductivity material

• thermal insulation

What are examples of thermal insulation?

• cavity insulation,

• loft insulation,

• double glazed windows

• draught excluders

Whats cavity walls and what do they reduce?

1. air gap reduces conduction; foam insulation reduces convection.

What is loft insulation and what does it reduce?

2. fibreglass traps air to reduce conduction and convection.

What are double glazed windows and what do they reduce?

3. air gap between glass layers reduces conduction.

What do draught excluders reduce and what are they?

4. reduce convection around doors and windows by blocking gaps

Waste energy is in most ______ _________

energy transfers

Efficiency is used to measure what?

the amount of useful energy transfered

What is useful energy?

The amount of input energy that is used and not wasted

the less engery wasted the more______

efficient

How can you improve efficiency?

Minimising the energy wasted by:

• insulating

• lubricating

• making objects more streamlined

Useful energy out put is usually not equal to the total energy input

.

How efficient are electric heaters?

usually 100% (electrostatic → thermal)

___device is 100% efficient ( 1 exception, ______ _________)

NO, electric heaters

all energy ends up in the _______ energy store

thermal