Energy changes in a system -
- Energy is the ability of an object to do work. When work is done BY an object, energy is
transferred FROM the object. When work is done ON an object, energy is transferred TO the
object. For example, when pushing a box you do work on the box so transfer energy to it.
- Work done = energy transferred.
- Energy and work done are measured in joules (J). 1kJ = 1000J, 1MJ = 1,000,000J.
- The total amount of energy in a closed system (object or group of objects unaffected by things
happening outside of it) is constant.
Types of energy:
- Kinetic – Moving objects.
- Chemical – In the bonds between atoms (e.g. fuel, batteries and food).
- Thermal – Due to the random motion of particles in an object.
- Internal – Due to random motion and position of particles in an object.
- Gravitational potential – Due to its position in a gravitational field.
- Magnetic – Due to its position in a magnetic field.
- Electrostatic – Due to its position in an electric field.
- Elastic potential – When its shape is changed.
- Nuclear – Stored between particles in the nuclei of atoms (only released in fusion or fission
reactions).
Energy changes in a system:
- When a tennis ball is thrown upwards energy is transferred from kinetic to gravitational
potential. Total amount of energy possessed is constant.
- When a football is kicked energy is transferred from chemical energy in foot to kinetic energy
of ball.
- In a wind up toy energy is transferred from elastic potential to kinetic energy store.
- When we heat water in a kettle energy is transferred from electrostatic energy to thermal
store.
- When a driver brakes they transfer energy from kinetic store to thermal store (in brakes).
- When we hold magnets close together and release them energy is transferred from magnetic
to kinetic store.
- When we burn wood energy is transferred from chemical to thermal store.
- When we power a filament bulb using a battery energy is transferred from chemical to thermal
store.
- The specific heat capacity is the amount of energy it takes to increase the temperature of 1kg
of that material by 1C.
- Water has a SHC of 4200J/kg C
- Decrease in elastic potential energy = increase in kinetic energy.
REQUIRED PRACTICAL: Investigate how effective different materials are as thermal
insulators:
, 1. Wrap a beaker in an insulating jacket (such as aluminium foil).
2. Pour in some hot, but not boiling water.
3. Place a lid with a hole with a thermometer in.
4. Measure the initial water temperature.
5. Measure the water temperature at set intervals (e.g. every 2 minutes).
6. Repeat this experiment with different insulators (e.g. white card, black sugar paper).
- The thermometer has a resolution of 1C.
Power -
- Power is the rate at which energy is transferred or at which work is done.
REQUIRED PRACTICAL - How to measure the specific heat capacity of a material:
- Immersion heater connected to power supply via joulemeter.
- Insulating the cylinder reduces the heat loss to the surroundings.
- Connect heater to ammeter in series and voltmeter in parallel.
National and global energy resources -
- The main energy resources in the UK are non-renewable (coal, oil, gas nuclear, formed from
remains of animals that died millions of years ago) and renewable (biomass, tidal, hydroelectric,
wave, wind, solar, geothermal)
- Non-renewable means when they are used up, no more are left as they take millions of years
to form. They are cheap and convenient. Very popular (most of our electricity generated from it).
Bad for environment as release greenhouse gases (contribute to global warming). Leads to
release of sulphur dioxide which can cause acid rain and breathing problems in humans.
- Steam produced in a furnace is used to drive turbines. The turbines drive a generator.
- Nuclear power generates 20% of electric in the UK. Uranium and plutonium are the main
sources. Non-renewable but will last for thousands of years. Do not contribute to global warming
but radioactive waste produced has to be stored carefully and there is a risk of nuclear
meltdown.
- A renewable energy resource won’t run out. They are replenished immediately or quickly.
- Biomass means biological material. When burned the heat released generates electricity on a
small scale or heats buildings directly. Biofuels are carbon neutral as absorb CO2 from
atmosphere whilst growing and release again when burnt.
- Tides can produce large amounts of electricity reliably when huge amounts of water move in
and out of estuaries. They are very expensive to build. Underwater gates open to allow water
through, close at high tide, and open to allow water to turn a turbine at low tide.
- Hydroelectric power stations rely on the movement of water. A dam is built across a river
making a reservoir and the water drives a turbine. They can have negative social and
environmental impacts (people moving from homes, forests cut down, habitats destroyed). They
produce large amounts of electric reliably. Pumped storage is when the demand for electricity is
LOW, excess energy from other sources drives generates in reverse to pump water back into
upper reservoir. Stored water released when demand is HIGH.
- Wave generators: Air is compressed and forced rapidly through a turbine. As water level falls
- Energy is the ability of an object to do work. When work is done BY an object, energy is
transferred FROM the object. When work is done ON an object, energy is transferred TO the
object. For example, when pushing a box you do work on the box so transfer energy to it.
- Work done = energy transferred.
- Energy and work done are measured in joules (J). 1kJ = 1000J, 1MJ = 1,000,000J.
- The total amount of energy in a closed system (object or group of objects unaffected by things
happening outside of it) is constant.
Types of energy:
- Kinetic – Moving objects.
- Chemical – In the bonds between atoms (e.g. fuel, batteries and food).
- Thermal – Due to the random motion of particles in an object.
- Internal – Due to random motion and position of particles in an object.
- Gravitational potential – Due to its position in a gravitational field.
- Magnetic – Due to its position in a magnetic field.
- Electrostatic – Due to its position in an electric field.
- Elastic potential – When its shape is changed.
- Nuclear – Stored between particles in the nuclei of atoms (only released in fusion or fission
reactions).
Energy changes in a system:
- When a tennis ball is thrown upwards energy is transferred from kinetic to gravitational
potential. Total amount of energy possessed is constant.
- When a football is kicked energy is transferred from chemical energy in foot to kinetic energy
of ball.
- In a wind up toy energy is transferred from elastic potential to kinetic energy store.
- When we heat water in a kettle energy is transferred from electrostatic energy to thermal
store.
- When a driver brakes they transfer energy from kinetic store to thermal store (in brakes).
- When we hold magnets close together and release them energy is transferred from magnetic
to kinetic store.
- When we burn wood energy is transferred from chemical to thermal store.
- When we power a filament bulb using a battery energy is transferred from chemical to thermal
store.
- The specific heat capacity is the amount of energy it takes to increase the temperature of 1kg
of that material by 1C.
- Water has a SHC of 4200J/kg C
- Decrease in elastic potential energy = increase in kinetic energy.
REQUIRED PRACTICAL: Investigate how effective different materials are as thermal
insulators:
, 1. Wrap a beaker in an insulating jacket (such as aluminium foil).
2. Pour in some hot, but not boiling water.
3. Place a lid with a hole with a thermometer in.
4. Measure the initial water temperature.
5. Measure the water temperature at set intervals (e.g. every 2 minutes).
6. Repeat this experiment with different insulators (e.g. white card, black sugar paper).
- The thermometer has a resolution of 1C.
Power -
- Power is the rate at which energy is transferred or at which work is done.
REQUIRED PRACTICAL - How to measure the specific heat capacity of a material:
- Immersion heater connected to power supply via joulemeter.
- Insulating the cylinder reduces the heat loss to the surroundings.
- Connect heater to ammeter in series and voltmeter in parallel.
National and global energy resources -
- The main energy resources in the UK are non-renewable (coal, oil, gas nuclear, formed from
remains of animals that died millions of years ago) and renewable (biomass, tidal, hydroelectric,
wave, wind, solar, geothermal)
- Non-renewable means when they are used up, no more are left as they take millions of years
to form. They are cheap and convenient. Very popular (most of our electricity generated from it).
Bad for environment as release greenhouse gases (contribute to global warming). Leads to
release of sulphur dioxide which can cause acid rain and breathing problems in humans.
- Steam produced in a furnace is used to drive turbines. The turbines drive a generator.
- Nuclear power generates 20% of electric in the UK. Uranium and plutonium are the main
sources. Non-renewable but will last for thousands of years. Do not contribute to global warming
but radioactive waste produced has to be stored carefully and there is a risk of nuclear
meltdown.
- A renewable energy resource won’t run out. They are replenished immediately or quickly.
- Biomass means biological material. When burned the heat released generates electricity on a
small scale or heats buildings directly. Biofuels are carbon neutral as absorb CO2 from
atmosphere whilst growing and release again when burnt.
- Tides can produce large amounts of electricity reliably when huge amounts of water move in
and out of estuaries. They are very expensive to build. Underwater gates open to allow water
through, close at high tide, and open to allow water to turn a turbine at low tide.
- Hydroelectric power stations rely on the movement of water. A dam is built across a river
making a reservoir and the water drives a turbine. They can have negative social and
environmental impacts (people moving from homes, forests cut down, habitats destroyed). They
produce large amounts of electric reliably. Pumped storage is when the demand for electricity is
LOW, excess energy from other sources drives generates in reverse to pump water back into
upper reservoir. Stored water released when demand is HIGH.
- Wave generators: Air is compressed and forced rapidly through a turbine. As water level falls
