Topic 1 - Energy

Question 1

Define a closed system

Answer 1

A closed system is when a system does not allow any matter to leave or enter.

Question 2

What are the four ways to transfer energy?

Answer 2

• – Electrically
• – Mechanically
• – By heating
• – By radiation

Question 3

What are the eight energy stores?

Answer 3

• – Kinetic energy
• – Gravitational potential energy
• – Elastic energy
• – Chemical energy
• – Thermal energy
• – Electrosatic energy
• – Nuclear energy
• – Magnetic energy

Question 4

What is the equation for kinetic energy?

Answer 4

Kinetic energy = 1/2mv^2

Question 5

What is the equation for gravitational potential energy?

Answer 5

GPE = mgh

Question 6

What is the equation for elastic potential energy?

Answer 6

Elastic potential energy = 1/2ke^2

Question 7

What happens to the kinetic and gravitational potential energy as an object falls?

Answer 7

Loss in GPE = Gain in kinetic energy

Question 8

What is the equation for specific heat capacity?

Answer 8

SHC = massspecific heat capacitychange in temperature

Question 9

What is the conservation of energy principle.

Answer 9

Energy cannot be created or destroyed, it can only be transferred usefully, stored or dissipated.

Question 10

What is the equation for power?

Answer 10

Power = energy / time

OR

Power = work done / time

Question 11

What states of matter does conduction and convection occur in?

Answer 11

Conduction occurs in only solids. Convection occurs in liquids and gases.

Question 12

Explain how conduction works.

Answer 12

When a soid is heated, energy is transferred to its thermal store. This energy is stored as the kinetic energy of the particles which causes the particles to vibrate on the spot. The particles vibrate and collide with the neighbouring particles. By colliding with neighbouring particles, energy is transferred. This process continues until energy is transferred to the other side of the object.

Question 13

How do lubricants help to reduce unwanted energy transfers?

Answer 13

Lubricants reduce the friction between objects which means less energy is wasted or dissipated into the surroundings.

Question 14

What are some examples of thermal insulation and give a brief description of each.

Answer 14

• – Draught excluders: placed around doors or windows to reduce transfers by convection
• – Cavity wall insulation: cavity wall air gap filled with foam to reduce transfers by convection
• – Loft insulation: reduces convection currents in lofts
• – Double-glazed windows: has an air gap to trap heat and reduces transfers by conduction

Question 15

What is the general equation for efficiency?

Answer 15

Efficiency = useful output / total input

Question 16

What is the difference between non-renewable and renewable energy resources?
Give examples of each.

Answer 16

Non-renewable resources will eventually run out whereas renewable resousrces will never run out because they are being replaced at the same rate that they are used up.

Non-renewable resources:
— Coal, Oil, Natural gas

Renewable resources:
— Wind, Solar, Tidal, Hydroelectric, Wave, Geothermal, Bio-fuel

Question 17

What are the advantages and disadvantages of wind power?

Answer 17

Advantages:

• – No pollution
• – Minimal running costs due to no fuel costs
• – No permanent damage to landscape

Disadvantages:

• – Noise pollution
• – Visual pollution
• – Initial high costs
• – Unreliable as there is not always wind

Question 18

What are the advantages and disadvantages of solar energy?

Answer 18

Advantages:

• – No visual pollution
• – No noise pollution
• – Minimal running cost

Disadvantages:

• – Unreliable as there is not always sun
• – High initial start up costs