Combined Physics - 6.1

Question 1

In physics, what is a ‘system’?

Answer 1

A system is an object or group of objects

Question 2

What changes are involved in the way energy is stored in an object projected upwards?

Answer 2

Chemical Energy → Kinetic Energy → Gravitational Potential Energy

Question 3

What changes are involved in the way energy is stored in a moving objecting hitting an obstacle?

Answer 3

Kinetic Energy → Sound Energy / Thermal Energy

Question 4

What changes are involved in the way energy is stored in an object accelerated by a constant force such as gravity when dropping a ball?

Answer 4

Gravitational Potential Energy → Kinetic Energy

Question 5

What changes are involved in the way energy is stored in a vehicle slowing down?

Answer 5

Kinetic Energy → Heat Energy

Question 6

What changes are involved in the way energy is stored bringing water to a boil in an electric kettle?

Answer 6

Electrical Energy → Thermal Energy

Question 7

What equation is used to calculate the kinetic energy of a moving object?

Answer 7

Question 8

How can the gravitational potential energy gained by a raised object above the ground be calculated?

Answer 8

Question 9

What is the specific heat capacity of a substance?

Answer 9

The amount of energy required to raise the temperature of 1kg of the substance by 1^oC

Question 10

What is power?

Answer 10

The rate at which energy is transferred / the rate at which work is done

Question 11

What are the three equations associated with power?

Answer 11

Question 12

What energy transfer is equal to a power of 1 watt?

Answer 12

1 joule per second

Question 13

Lifting an object takes 10’000J – machine A can do this in 50s but machine B takes 100s. Which machine is more powerful?

Answer 13

Both machines transfer the same amount of energy, but machine A is more powerful:

P = W ÷ t

Machine A has a power of 200W (10’000 ÷ 50) whilst machine B has a power of 100W (10’000 ÷ 100)

Question 14

What is the conservation of energy principle?

Answer 14

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

Question 15

What happens to the energy transfer in a closed system?

Answer 15

There is no net change to the total energy

Question 16

When energy is transferred not all of it is transferred usefully (some energy is dissipated). What term is used to describe this dissipated energy?

Answer 16

Wasted energy

Question 17

How does lubrication reduce unwanted energy transfers?

Answer 17

Lubrication reduces frictional forces

Question 18

How does insulation reduce unwanted energy transfers?

Answer 18

Insulation reduces the rate of energy transfer by heating

Question 19

List some examples of insulation

Answer 19

• Cavity wall insulation (reduces convection)
• Loft insulation (reduces convection)
• Double-glazed windows (reduces conduction)
• Draught excluders (reduces convection)

Question 20

What is conduction?

Answer 20

Conduction is the process where vibrating particles transfer energy to neighbouring particles (occurring mainly in solids)

Question 21

What is convection?

Answer 21

Convection is the process where energetic particles move away from hotter regions to cooler ones (occurring in fluids)

Question 22

In terms of conduction across the material what does an increased thermal conductivity of a material cause?

Answer 22

Increased thermal conductivity of a material means a higher rate of energy transfer

Question 23

How do walls and the thermal conductivity of the material affect the rate of cooling in a building?

Answer 23

Thick walls made from a material with low thermal conductivity slows the rate of energy transfer (so the building remains warmer for longer)

Question 24

What is the equation for energy efficiency for a given energy transfer, with regard to energy input/output?

Answer 24

Question 25

What is the equation for energy efficiency for a given energy transfer, with regard to power input/output?

Answer 25

Question 26

What are the main energy resources available on Earth?

Answer 26

• Fossil fuels
• Nuclear fuel
• Bio-fuel
• Wind
• Hydro-electricity
• Geothermal
• Tidal
• Solar
• Water waves

Question 27

List the types of fossil fuel

Answer 27

• Coal
• Oil
• Gas

Question 28

What does the term non-renewable energy resource mean (and list them)?

Answer 28

Non-renewable energy resources will run out, e.g. coal, oil, natural gas and nuclear

Question 29

What does the term renewable energy resource mean (and list them)?

Answer 29

Renewable energy resources can be replenished (will never run out), e.g. solar, wind, water waves, hydro-electricity, bio-fuel, tidal and geothermal

Question 30

What uses do we have for energy resources?

Answer 30

• Transport
• Electricity generation
• Heating

Question 31

Describe wind power and how it is used

Answer 31

Wind turbines are placed in exposed areas where rotating blades turn a generator producing electricity. They are non-polluting (though spoil the view / are noisy)

Question 32

Describe solar cells and how they are used

Answer 32

Solar cells generate electricity directly from sunshine. They are non-polluting (though don’t work at night)

Question 33

Describe geothermal power and how it is used

Answer 33

Geothermal power relies on naturally occurring hot rocks which heat pumped water creating steam. They cause very little damage to the environment (though there are few locations available)

Question 34

Describe hydro-electric power and how it is used

Answer 34

Hydro-electric power uses falling water (usually falling over a dam). Though this is clean energy, the construction of the dam can be extremely damaging (high levels of concrete / habitat damage etc…)

Question 35

Describe water wave power and how it is used

Answer 35

Water wave power uses wave-powered turbines around the coast generating electricity.

Question 36

Describe tidal barrages and how they are used

Answer 36

Tidal barrages are dams built across river estuaries, using the Sun and Moon’s gravity where the tide turns a turbine. Non-polluting they do change the habitat

Question 37

Describe bio-fuels and how they are used

Answer 37

Bio-fuels are made from plants and waste which are supposedly carbon neutral. Costs are high and bio-fuel crops reduce space for food crops

Question 38

What energy resources are used for transport?

Answer 38

Petrol / diesel from oil is mainly used (though coal for steam engines / bio-fuels are also used)

Question 39

What energy resources are used for heating?

Answer 39

Natural gas is mainly used for heating, though coal and electric heaters are also used. Solar water heaters are also becoming more common

Question 40

Why are non-renewable energy resources so abundantly used?

Answer 40

Non-renewables are relatively cheap and are reliable (there is enough to meet current demand)

Question 41

What environmental issues do non-renewable energy resources create?

Answer 41

Fossil fuels release CO₂ into the atmosphere contributing to global warming. Acid rain is also caused, along with nuclear power potential disasters / oil spillages etc…

Question 42

What current trends in energy resource use exist at present?

Answer 42

The world currently heavily depends on fossil fuels, though people are increasing wanting to use more renewables (e.g. electric cars)

Question 43

Why is renewable energy uptake limited?

Answer 43

Currently renewable energy isn’t as reliable or cost effective as non-renewable energy. Politics of increased initial prices for renewable energy resources also often gets in the way