Chapter 1- Energy

Question 1

GPE equation

Answer 1

Ep=mgh

Question 2

Kinetic Energy equation

Answer 2

E = 0.5x m x v²

Question 3

Work Done equation

Answer 3

Work=FS

s=distance

Question 4

what is efficiency

Answer 4

efficiency tells us how good a transformer is at doing its job

Question 5

efficiency equation

Answer 5

Efficiency = useful energy ÷ total energy

Question 6

does efficiency have units?

Answer 6

no

Question 7

power equation

Answer 7

power(watts(w))=energy(J)/time(s)

Question 8

calculating efficiency from power

Answer 8

Efficiency=useful power output/total power input

Question 9

what is a Mw

Answer 9

mega watt- 1 million watts

Question 10

what is a kw

Answer 10

a kilowatt-1 thousand watts

Question 11

what is thermal energy?

Answer 11

A type of energy that will flow from a warm area to a cold areas until it reaches the temperature of the surrounding(until it is all equal)

Question 12

list the three ways energy can move

Answer 12

conduction, convection or radiation

Question 13

what is a similarity between convection and conduction?

Answer 13

both involve particles gaining kinetic energy

Question 14

what is infrared radiation?

Answer 14

electromagnetic waves between visible light and microwaves

Question 15

Momentum equation ( involving mass and velocity)

Answer 15

Momentum = mass X velocity

Question 16

Why doesn’t a bungee jumper bounce back to the top?

Answer 16

Because the gravitational field strength is pulling you down stoppiy you from going to your original height

Question 17

what is work done

Answer 17

when a force moves an object through a distance

Question 18

what is mechanical work

Answer 18

energy transferred from one object to another by force

Question 19

what is waves (energy transforming/transfers)

Answer 19

Light + other types of energy transferred from one energy store to another

Question 20

Heating (energy transforms/ transfers)

Answer 20

Heating an object transfers energy from the object’s internal store of energy

Question 21

how does conduction transfer energy?

Answer 21

conduction passes energy from one particle to another (by vibrating) the partices do not move

Question 22

why are metals good thermal conductors?

Answer 22

They have free electrons to carry energy

Question 23

what is specific heat capacity?

Answer 23

the amount of energy required to raise 1kg of material by 1℃

Question 24

specific heat capacity equation

Answer 24

Energy=mass(kg)x specific heat capacity(J/Kg℃)x temperature change(℃)

Question 25

Why are metals good thermal conductors and non metals not so good

Answer 25

metals are good thermal conductors because they have free electrons to carry energy. non metal solids are usualy poor conductors because they need atomic vibrations to carry energy

Question 26

advantages of wind and solar power

Answer 26

•Low running costs •Don't release pollutants •Don't damage the environment •Getting cheaper every year

Question 27

Disadvantages of wind and solar power

Answer 27

•High upfront cost •Making them does produce pollutants •Dependent on the weather 0149No way to inc supply in a time of demand

Question 28

Advantages and disadvantages of hydroelectricity and tidal barrages

Answer 28

Advantages: •Renewable •large amounts of energy transferred •no pollutants •Reliable •Hydroelectricity- immediate response to increased demand •Running costs fairly low •Work on both large and small scales Disadvantages: •Often flood •Often big impact on environment (flood habitat, noise pollution, installation destroys some habitats •Stops boats+ fish swimming up stream Initail set up is expensive

Question 29

what is specific heat capacity?

Answer 29

the amount of energy required to raise the temperature of 1kg of material by 1 degrees Celsius

Question 29

what is specific heat capacity?

Answer 29

the amount of energy required to raise the temperature of 1kg of material by 1 degrees Celsius

Question 30

what units is g measured in?

Answer 30

N/kg

Question 31

When an object falls describe the energy changes

Answer 31

When an object falls the GPE store is converted into the kinetic energy store Without resistance energy lost from gpe=energy gained in Ek store (However in real life some energy is transferred to other energy stores e.g thermal energy of the object and its surroundings

Question 32

What is the power of an appliance defined as ?

Answer 32

The Power of the appliance (in watts)-is the energy it transforms in Joules per second(J/s) Aka watts (W)

Question 33

Why are metals good conductors of thermal energy

Answer 33

Because they have free electrons to carry energy

Question 34

How does thermal energy behave

Answer 34

Thermal energy will flow from a warm area to a colder area until the temperature of the surroundings are even(almost like diffusion)

Question 35

Why are non-metals not good at conducting thermal energy

Answer 35

Because they need atomic vibrations to carry energy

Question 36

What is conduction?

Answer 36

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

Question 37

How does the energy transfer in conduction which energy transfers?

Answer 37

Energy transferred by heating is transferred to the thermal energy store of the object. this energy is shared across the kinetic energy stones of the particles in the object.

Question 38

What does a hot object emit

Answer 38

Infrared radiation

Question 39

White surfaces in terms of infrared radiation (are they good absorbers/ emitters, are they good or bad reflectors)

Answer 39

White surfaces are good reflectors of it radiation But poor emitters and absorbers of ir radiation

Question 40

Shiny Surfaces in terms of infrared radiation (are they good absorbers/ emitters, are they good or bad reflectors)

Answer 40

Poorer absorbers of radiation than dull surfaces of the same colour Poorer emitters and better reflectors than dull surfaces of the same colour

Question 41

Black surfaces in terms of infrared radiation (are they good absorbers/ emitters, are they good or bad reflectors)

Answer 41

Good emitters Good absorbers Poor reflectors Of radiation

Question 42

Space blankets are designed to keep runners warm after marathons. They are shiny on both sides. Suggest why the shiny sides may help keep runners warm

Answer 42

The runner is hotter than their surroundings, so heat needs to be trapped inside the blanket. The inner surface of the blankets is shiny to reflect any infra-red radiation from the runner's body back to the runner. Any heat that is transferred to the blanket would then be emitted as infra-red to the outside world, so the outer side is shiny to reduce the infra-red emission to the surroundings.

Question 43

List two ways to reduce friction

Answer 43

Using Lubricants Using smoother surfaces

Question 44

how does Surface Area affect emission of radiation

Answer 44

Bodies with a large surface area will emit radiation faster.