P1 Flashcards
Define Specific Heat Capacity
The amount of energy needed to raise the temperature of 1 kg of a substance by 1 degree Celsius
Define power
Rate at which energy is transferred
Describe energy changes involved when a ball is thrown upwards and then returns to its starting position ( 3 marks)
Upwards - KE transfers to GPE
Peak - Maximum GPE - zero KE
Downwards: GPE transferred to KE
Describe energy transfers for a bungee jumper ( 3 marks)
When falling, GPE transferred to KE
Cord tightens, KE transferred and stored as EPE
At lowest point, the jumper’s initial GPE = EPE stored in the cord
Explain why a bungee jumper slows down once the cord begins to stretch ( 2 marks)
KE decreases since it is converted to EPE
KE proportional to velocity squared as KE decreases, velocity decreases
3 examples of chemical energy stores
Food
Fuel
Batteries
What is the law of energy conservation
Energy cannot be created or destroyed
State changes in the total energy of any action
total energy of the system remains constant due to conservation of energy
What is waste energy
Energy that is not used for its desired purpose
Describe the energy changes that occur in a filament light-bulb ( 2 marks)
Electrical energy is transferred into light and heat energy
Light is a useful energy form, heat is waste energy
How can efficiency of a system be increased?
Reducing waste output via lubrication, thermal insulation
Recycling waste output
Do double-glazed windows have a higher or lower thermal conductivity than single-glazed windows
Lower, meaning less energy transfers through them
What factors affect the rate of cooling of a building ( 2 marks)
Thickness of the walls
Thermal conductivity of the wall
3 ways to reduce heat loss in a building
double glazing
loft and wall insulation
thicker walls
How can the efficiency of a mechanical machine with moving parts be improved? ( 2 marks)
Lubricate any moving parts to reduce the friction and therefore energy loss due to heating
How can the efficiency of a radiator be improved ( 2 marks)
Installing metal foil sheets behind the radiator to reflect back the heat into the room
What is a renewable energy resource?
Energy source which can be replenished as it used up
Four examples of renewable energy resources
Wind energy
Hydro-electricity
Tidal energy
Solar energy
Example of a non-renewable energy resource
Fossil fuels
Four ways energy can be transferred
Mechanical
Electrical
Heat
Radiation
Two advantages of generating power using gas rather than coal
Flexible generation - gas power stations can be switched on/off more readily
Lower emissions of carbon dioxide
Two disadvantages of using renewable energy resources to generate power
Output often determined by external factors - supply uncertain
Generating power through other means is often more efficient and economically beneficial
Three advantages of fossil fuels as an energy resource
Reliable - not dependent on external factors
Can produce large amounts of energy for a given quantity
still relatively abundant, so cost-effective
Three advantages of nuclear power
Very large amounts of energy for relatively small quantities of fuel
Doesn’t release gg
Low fuel costs
