P1 : Physics

What is specific heat capacity?

The amount of the energy needed to increase the temperature of 1kg of a substance by 1 degree.

What is the formula for SHC?

Change in energy = mass x SHC x temperature change

△E =m x c x △degree

What is the formula for finding SHC?

SHC = energy change/mass x temperature change

What are the 8 energy stores?

1. Magnetic

2. Kinetic

3. Electrostatic

4. Thermal

5. Nuclear

6. Gravitational potential

7. Elastic potential

8. Chemical

What are the 4 ways energy can be transferred?

1. Mechanically

2. Electrically

3. By heating/thermally

4. Radiation (light or sound)

What is a system?

A single or group of objects that when changed transfer energy.

What is the principle of conservation?

Energy can only be transferred usefully, stored or dissipated (lost) but never destroyed nor created.

What are the 2 methods to reduce energy waste?

1. Lubrication

2. Streamlining

What is lubrication?

Reducing friction to prevent thermal energy loss.

What is streamlining?

Reducing the impacts of air resistance - reducing loss of energy to thermal energy stores.

What is thermal conductivity?

A measure of how quick energy is transferred by conduction through a metal.

Materials with low conductors are —

Insulators

What are the ways a home is kept warm?

1. Thick walls = stops conduction = low thermal conductivity to reduce thermal energy loss

2. Walls insulation = stops conduction = reduces thermal heat loss

3. Windows (double glazing) = stops conduction = trapped air acts as insulated

4. Loft insulation = stops conduction currents

5. Drought extenders = prevent conduction current and thermal energy loss

What is conduction?

Conduction is the transfer of thermal energy by the vibration of particles in a solid.

How is thermal energy transferred in a solid?

When a solid is heated the energy is transferred to the kinetic energy store. The particles in the object vibrate as they gather energy ands the thermal energy passes from the hot to the cold end.

Define convection.

Convection is the transfer of thermal energy in a fluid.

How is thermal energy transferred in a fluid?

When a fluid is heated the particles gain energy so move and spread out becoming less dense. The warmer regions of the fluid are less dense so rise and the colder regions sink as they are more dense. This becomes a convection current as a steady flow between the regions continues until the thermal energy has been transferred fully.

Define kinetic energy.

The energy an object has because it is moving.

What does kinetic energy depend on?

1. Mass

2. Speed

What is the formula for kinetic energy?

Kinetic energy = 0.5 x mass x velocity(squared)

Ek = 0.5 x m x v(squared)

J = 0.5 x kg x m/s

Define elastic potential energy.

The energy an object has when squashed or stretched.

What is the formula for elastic potential energy?

Elastic potential energy = 0.5 x spring constant x extension(squared)

Ee = 0.5 x K x e(squared)

J = 0.5 x N/m x m(squared)

Define power.

The rate at which energy is being used.

What is the formula for power?

Power = work done/time

W = J/s

Define gravitational potential energy.

The amount of energy an object has due to it’s position above the ground.

What does gravitational potential energy depend on?

1. Mass

2. Height

What is the formula for gravitational potential energy?

Ep = mass x gravitational field strength x height

Ep = m x g x h

J = kg x N/kg x m

What should be used if gravitational field strength is not given?

9.8 N/kg

What is the relationship between GPE and KE?

GPE lost = KE gained

GPE gained = KE lost

Define efficiency.

How much energy is usefully transferred.

What is the formula used for efficiency?

Efficiency = useful energy output/total energy input x 100

Efficiency = useful power output/total power input x 100

How do you investigate the SHC of a solid material?

• Récord the mass of your block (using a top pan balance) in kg

• Measure the initial temperature of the block

• Connect to a circuit and power supply

• Set the voltage of a power supply to 12v

• Turn on the power supply

• Record the current and potential difference

• Take readings of the temperature every minute four 10 minutes

Define a non-renewable energy source.

Resources that are not being made at the same rate they are bring used so will run out: finite.

Define a renewable energy source.

Resources that can be made at the same rate that they are being used - they will not run out as they are replenishable.

What are the 4 non-renewable resources?

1. Coal

2. Oil

3. Natural gas

4. Nuclear

What are the 7 renewable energy resources?

1. Geothermal

2. Solar

3. Biofuel

4. Hydroelectricity

5. Water waves

6. Tidal

7. Wind

How does hydroelectricity work?

Flooding a valley to build a dam - water is allowed out through energy generating turbines.

What are the advantages of hydroelectricity?

• Reliable

• Can meet demand

• Can be done remotely

• Low running costs

What are the disadvantages of hydroelectricity?

• Plants rot and release carbon due to flooding

• Habitats lost

• High initial costs

How does wave power work?

Lots of small wave powered turbines connected to a generator.

What are the advantages of wave power?

• Useful on islands

• No carbon emissions

• No pollution

What are the disadvantages of wave power?

• Disturbs the sea bed

• Unreliable

• High initial costs

How do tidal barrages work?

Big dams across rivers that flow water through due to tides where turbines generate electricity.

What are the advantages of tidal barrages?

• Reliable

• No carbon emissions

• High generating power

What are the disadvantages of tidal barrages?

• Hábitat damage

• Fish killed

• Visual pollution

• Prevents access from boats

How does wind power work?

The wind turned the propeller which turns the generator and moto causing energy to be generated.

What are the advantages of wind power?

• No landscape damage

• No carbon emissions

• Low costs

What are the disadvantages of wind power?

• Unreliable

• Noise and visual pollution

• High initial costs

How does solar energy work?

Radiation from the sun provides thermal heat generating electricity.

What are the advantages of solar power?

• No running costs

• No carbon emissions

• Reduced energy bills

What are the disadvantages of solar power?

• Weather dependent

• Takes up space

• Small scale of generation

How does geothermal work?

Energy stored thermally beneath the Earth’s solid surface due to radioactive decay turning injected water into steam through generating turbines.

What are the advantages of geothermal?

• Reliable

• Good for heating and cooling

• No carbon emissions

What are the disadvantages of geothermal?

• Location specific

• High initial costs Generates waste

• Generates waste

How do fossil fuels work?

Burnt to release thermal energy which turns water to steam to turn turbines.

What are the advantages of fossil fuels?

• Cheap to extract

• Easy to export

• Scaled to meet demand

What are disadvantages of fossil fuels?

• Non-renewable

• Contributes to global warming

• High costs to refine

How does nuclear energy work?

Nuclear fission process.

What are the advantages of nuclear energy?

• No greenhouse gas emitted

• Lots of energy produced

• Scales to meet demand

What are the disadvantages of nuclear energy?

• Non-renewable

• Produces radioactive waste

• High set up costs

How does biofuel work?

Plant matter is burnt to release thermal energy.

What are the advantages of biofuel?

• Net-zero

• Renewable

• Reliable

What are the disadvantages of biofuel?

• Large areas of land needed

• Habitats destroyed

• Food can not be grown simultaneously

• High costs to refine

What are the trends in energy resource us?

Fossil fuels are still widely used to meet demand and rapidly changing populations.

More people want more renewable energy resources due to the environmental benefits.

Why is use of renewable resources limited?

1. Money = it costs a plot of money to set up and switch to renewable energy resources.

2. Arguments on where they should be built.

3. Reliability = a lot of energy resources are not as reliable as fossil fuels as they are dependent on external factors such as the sun and wind.

4. Politics = opinions on renewable energy change per party.