Energy

Question 1

Energy is _______ between stores

Answer 1

transferred

Question 2

When energy is transferred to an object, energy is…

Answer 2

stored in of the object’s energy stores

Question 3

When a system changes, what happens?

Answer 3

Energy is transferred

Question 4

What is a system?

Answer 4

An object or group of objects

Question 5

What are closed systems?

Answer 5

Systems where matter and energy cannot enter or leave

Question 6

What is always the net change in total energy of a closed system?

Answer 6

Always 0

Question 7

A simple pendulum has what type of motion?

Answer 7

Oscillating motion

Question 8

In a simple pendulum, what is the energy transferred between?

Answer 8

Kinetic energy and gravitational potential energy

Question 9

Work done = ___ ______

Answer 9

Energy transferred

Question 10

Give 3 examples of work being done

Answer 10

• Initial force excerted by person to throw a ball upwards does work
• Friction between car’s brakes and its wheels does work (as car slows down)
• Collision between car and stationary object = normal contact force between car and object does work

Question 11

What is the energy transfer for when a person throws a ball upwards?

Answer 11

Chemical energy → Kinetic energy

Question 12

What is the energy transfer for when a car brakes?

Answer 12

Kinetic energy → Thermal energy

Question 13

What is the energy transfer for when a car collides with a stationary object?

Answer 13

Kinetic energy → Elastic potential + thermal energy + sound energy

Question 14

Energy can be ______ usefully, _____ or _______

Answer 14

Energy can be transferred usefully, stored or dissipated

Question 15

Energy cannot be ______ or _____

Answer 15

Created or destroyed

Question 16

Less energy that’s ‘wasted’, more _____ device is

Answer 16

efficient

Question 17

Name 3 ways we can improve the efficiency of energy transfers?

Answer 17

• Insulating
• Lubricating
• Streamlining objects

Question 18

How do friction and air resistance dissipate energy?

Answer 18

By heating the surroundings

Question 19

How can the flow in a system be represented?

Answer 19

By using Sankey diagrams

Question 20

Energy in kinetic energy store depends on object’s _____ and _______

Answer 20

mass and speed

Question 21

Greater an object’s mass + faster it’s going, the more

Answer 21

kinetic energy it has

Question 22

Raised objects have…

Answer 22

gravitational potential energy

Question 23

Higher the object raised = the more

Answer 23

gravitational potential energy / energy transferred to its store

Question 24

Stretching can transfer energy to ____ _______ ______ stores

Answer 24

elastic potential energy

Question 25

What is power?

Answer 25

The rate of energy transfer OR the rate of doing work

Question 26

1 Watt = ...

Answer 26

1 joule of energy transferred per second

Question 27

What makes a machine powerful?

Answer 27

If it can transfers a lot of energy in a short space of time

Question 28

What is conduction?

Answer 28

Process where vibrating particles transfer energy to neighbouring particles

Question 29

In conduction, how is energy transferred to object?

Answer 29

By heating

Question 30

In conduction, what store of an object is the energy transferred to?

Answer 30

Transferred to its thermal store & shared across kinetic energy stores of particles

Question 31

In conduction, what happens to particles when they're heated up (mention collsions + how it leads to conduction)?

Answer 31

* Particles heated vibrate more and collide with each other * These collisions cause energy to be transferred between particles' kinetic energy stores * = conduction

Question 32

What is thermal conduction?

Answer 32

A measure of how quickly energy is transferred through a material

Question 33

What do materials with high therma conductivity do?

Answer 33

Transfer energy between their particles quickly

Question 34

What is convection?

Answer 34

Where energetic particles move away from hotter to cooler regions

Question 35

In convection, how is energy transferred to object?

Answer 35

By heating to thermal store of liquid or gas

Question 36

Why can metal conduct heat?

Answer 36

Particles are tightly packed and have free electrons which can move and carry heat

Question 37

What do insulators do?

Answer 37

Reduce heat movement by conduction

Question 38

Illustrate the particle arrangement in a conductor

Answer 38

Question 39

Illustrate the particle arrangement in a insulator

Answer 39

Question 40

Explain why insulators do not conduct heat easily

Answer 40

* Particles not tightly packed and there's massive spaces between them * ∴ When particles vibrate = vibrations (heat energy) cannot be passed onto nearby particles easily

Question 41

Explain why hot air is more dense

Answer 41

1. Heated particles move faster and space between individual particles increase 2. Causes density of region being heated to decrease

Question 42

Why does warmer and a less dense region (particles) rise above a denser, cooler region (particles)? (simple answer)

Answer 42

Because fluids can flow

Question 43

When is a convection current created?

Answer 43

If there's a constant heat source