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PHYSICS GCSE > ENERGY > Flashcards

ENERGY Flashcards

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1
Q

Different energy stores ( eight)

A 
Thermal
kinetic
gravitational potential
elastic potential
chemical
magnetic
electrostatic 
nuclear
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2
Q

what is a system

A

a system is a single object or a group of objects

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3
Q

what happens when a system changes

A

when a system changes energy is transferred

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4
Q

what are closed systems

A

Closed systems are systems where neither matter nor energy can enter or leave. The net change in the total energy of a closed system is always zero

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5
Q

how is energy transferred mechanically

A

energy is transferred mechanically by a force doing work

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6
Q

how is energy transferred electrically

A

energy is transferred electrically by moving charges

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7
Q

how is energy transferred to and away from the kinetic energy store

A

anything that is moving has energy in its kinetic energy store. Energy is transferred to this store when an object speeds up and is transferred away when an object slows down

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8
Q

how does mass and speed affect kinetic energy

A

The greater its mass and the faster its going the more energy there will be in its kinetic energy store.

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9
Q

EQUATION FOR KINETIC ENERGY( include what they are measured in)

A

1/2mv2
energy- joules
mass-kg
speed-(m/s)2

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10
Q

what is required to lift an object in a gravitational field

A

work

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11
Q

how does height affect the gpe store

A

the higher the object is lifted, the more energy is transferred to this store.

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12
Q

what else affects the gpe store other than height

A

mass and the strength of the objects gravitational field

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13
Q

EQUATION FOR GRAVITATIONAL POTENTIAL ENRERGY( include what they are measured in)

A 
gpe=mgh
gpe- joules
mass-kg
gravitational field strength-n/kg
height-metres
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14
Q

what energy do falling objects transfer

A

when something falls energy from its gravitational potential energy store is transferred to its kinetic energy store

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15
Q

the rule for when objects fall when there Is NO AIR RESISTANCE

A

Energy lost from the gpe store = energy gained in the kinetic energy store

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16
Q

Energy lost from the gpe store =

A

energy gained in the kinetic energy store

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17
Q

how can energy be transferred to the elastic potential energy store

A

Stretching or squashing an object can transfer energy to its elastic potential energy store

18
Q

EQUATION FOR ELASTIC POTENTIAL ENERGY

A

E=1/2ke2
elastic potential energy-joules
spring constant- (n/m)
extension- metres

19
Q

DEFINITION SPECIFIC HEAT CAPACITY

A

Is the amount of energy needed to raise the temperature of 1kg of a substance by 1 degree

20
Q

EQUATION FOR SPECIFIC HEAT CAPACITY

A 
change in thermal energy=mass x specific heat capacity x temperature change
change in thermal energy- joules
mass-kg
shc- j/kg
temperature change- degrees
21
Q

Energy can never be…..

A

DESTROYED

22
Q

What is the conservation of energy

A

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

23
Q

what happens to energy when its transferred between stores (useful and dissipated energy)

A

not all of the energy is transferred usefully into the store that you want it to go into. Some of the energy is always dissipated

24
Q

energy transfer in a mobile phone

A

When you use the phone, energy is usefully transferred from the chemical energy store of the battery in the phone but some of this energy is dissipate to the thermal energy store of the phone.

25
Q

What is power

A

is the rate of energy transfer or the rate of work

26
Q

POWER EQUATIONS (with units)

A

P=E/T AND P=W/T

P- POWER
E-ENERGY TRANSFERRED
T-TIME

W-WORK DONE

27
Q

WHAT IS CONDUCTION

A

Conduction is the process where vibrating particles transfer energy to neighbouring particles

28
Q

where does conduction mainly happen in

A

happens mainly in solids

29
Q

Describe how energy is transferred through a solid by heating (convection)

A

Heating transfers energy to the particles kinetic energy stores. These particles vibrate and transfer energy between them which gradually transfers energy through the solid.

30
Q

what is thermal conductivity

A

thermal conductivity is how quickly energy is transferred through a material

31
Q

materials with high thermal conductivity…

A

transfer energy between their particles quickly

32
Q

WHAT IS CONVECTION

A

convection is where the energetic particles move away from hotter to cooler regions

33
Q

where does convection mainly happen in

A

liquids and gases

34
Q

how does convection happen in liquids and gases

A

energy is transferred by heating to the thermal store of the liquid or gas, this energy is shared across the kinetic energy store of the gas or liquids particles. When you heat a region of a gas or liquid, the particles move faster and the space between individual particles increases
because liquids can flow the warmer and less dense regions will rise above denser, cooler regions.

35
Q

convection currents

A

radiators can create convection currents
1.energy is transferred from the radiator to nearby air particles by conduction
2.the air near the radiator becomes warmer and less dense
3.the warm air rises and is replaced by cooler air, the cooler hair is then heated by the radiator
4.at the same time the previously heated air transfers energy to the surroundings it cools, becomes denser and sinks
this repeats causing a flow of air to circulate around the room

36
Q

ways to reduce unwanted energy transfers

A

lubrication and thermal insulation

37
Q

what happens to energy during friction

A

whenever something moves there’s usually at least one frictional force acting against it, This causes energy in the system to be dissipated

38
Q

how can you reduce friction from objects that are being rubbed together

A

lubricants eg-oil

39
Q

what does insulation do

A

insulation reduces the rate of energy transfer by heating

40
Q

How to prevent energy loss in a home (explain them)

A
  1. thick walls- the thicker the walls the lower their thermal conductivity and the lower the rate of energy transfer
  2. Cavity walls-air gap filled with foam reduces energy transfer by conduction. (inner and outer wall with air gap in the middle
  3. loft insulation- can reduce convection currents being created in lofts
  4. Double-Glazing- have an air gap between the two sheets of glass to prevent energy transfer by conduction
  5. Draught excluders- around doors and windows reduce energy transfer by convection
41
Q

EFFICIENCY EQUATION

A

Useful output energy transfer/total input energy transfer

         OR Useful power output/Total power input

PHYSICS GCSE (12 decks)

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