Energy

Question 1

Heat travels through a metal rod by…

Answer 1

Conduction

Question 2

Heat travels thorugh fluids by…

Answer 2

Convection

Question 3

Heat travels from the sun to the earth by…

Answer 3

Radiation

Question 4

A good emitter of heat is a…

Answer 4

Matte black surface

Question 5

A bad emitter of heat is a…

Answer 5

Shiny copper surface

Question 6

Types of energy stores are…

Answer 6

Kinetic - in a moving object
Chemical - a fuel or battery
Gravitational - an object above ground
Elastic/strain - a streched or squashed object
Thermal - due to substances temperature
Magnetic - 2 separated magnets (attract/repel)
Nuclear- radioactive decay

Question 7

The four pathways of energy transfers are…

Answer 7

Mechanically (when a force acts and something moves)
Electrically (when a current flows)
by heating (because of a temperature difference)
by radiation (waves) (a wave such as light, microvaves or sound)

Question 8

What is heat?

Answer 8

The heat an object contains is the amount of its thermal energy measured in joules of J.

Question 9

What is temperature?

Answer 9

The temperature of an object is to do with how hot or cold it is, measured using a thermometer. Note that the unit of temperatute is written as C degrees

Question 10

Which way does thermal energy travel from one object to another?

Answer 10

From hot objects to cool objects

Question 11

What is it called when both objects are at the same temperature after heating eachother?

Answer 11

They are in equilibrium

Question 12

What does the law of Conservation of Energy say?

Answer 12

That energy cannot be created or destroyed

Question 13

What is a unit of energy?

Answer 13

Jules (J) or kilojules (kJ)

Question 14

How does heat transfer by conduction?

Answer 14

Partciles near the heat source start to vibrate. The vibrations are passed from atom to atom, until the whole object is heated.

Question 15

What are good conducters?

Answer 15

Metals

Question 16

How does heat transfer by convection?

Answer 16

When a fluid is heated, the particles near the heat source gain energy and become less dense. They rise, and cooler particles fill their place. This repeats until a convection current is formed and the whole fluid is heated.

Question 17

How does the sun heat up the earth?

Answer 17

By emitting infrared radiation.

Question 18

What gives off infrared radiation?

Answer 18

All objects

Question 19

What colour emitts the most infared radiation?

Answer 19

Matte black

Question 20

Why are solids better at conducting heat than liquids and gases?

Answer 20

Because their particles are closer together.

Question 21

What surface is a good absorber of radiation?

Answer 21

A matte black surface

Question 22

How can you find out weight?

Answer 22

By multiplying mass and gravity

Question 23

How can you find out work?

Answer 23

By multiplying force and distance

Question 24

If a can is 4 N, and it goes up stairs of 3 M, what would the work be?

Answer 24

12 J

Question 25

What is work measured in?

Answer 25

Joules (J)

Question 26

How does a thermal power station heat up a kettle?

Answer 26

1. A fuel burns to heat water 2. Water boils to make steam 3. The steam drives the turbine 4. The turbine truns a generator 5. The generator produces current elctricity 6. Electricty provides current to heat kettle up.

Question 27

Why are fossil fuels bad for the environment?

Answer 27

When burned they release greenhouse gases

Question 28

What is power?

Answer 28

How fast energy is transferred from one form to another.

Question 29

What is power measured in?

Answer 29

Watts (W) or kilowatts (kW)

Question 30

How can we find out power?

Answer 30

By dividing energy by time

Question 31

If the energy to walk a couple steps is 100 J, and it takes 4 seconds, what would the power be.

Answer 31

25 W