Energy Changes Flashcards
(29 cards)
What is the equation for kinetic energy?
1⁄2 x Mass x (Velocity)^2
What is the equation for elastic potential energy?
1⁄2 x Spring Constant x (Extension)^2
What is the equation for gravitational potential energy?
Mass x Gravitational Field Strength x Height
What is the ‘Specific Heat Capacity’ of a substance?
The amount of energy needed to raise the temperature of 1 kilogram of a substance by 1 degree Celsius.
State the units for Specific Heat Capacity.
J/°C/kg
What is the definition of ‘Power’?
The rate at which energy is transferred (or the rate at which work is done).
State two equations for power.
power = energy transferred/time
power = work done/time
What is the unit of power?
Watt (W)
State 4 different stores of energy.
- Kinetic Energy
- Gravitational Potential Energy
- Elastic Potential Energy
- Chemical Energy
State the law of energy conservation
Energy cannot be created or destroyed it can only be transferred into different forms
What is waste energy?
The energy that is not used by the device for its desired purpose
State two equations to calculate efficiency.
Useful output energy transfer/ total input energy transfer
Useful power output/ total power output
Do double-glazed windows have a higher or lower thermal conductivity than single-glazed windows?
Lower, meaning less energy transfers through them.
What key factors affect the rate of cooling of a building?
The thickness of the walls
The thermal conductivity of the walls
State three methods of reducing 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?
Lubricate any moving parts to reduce the friction and therefore energy loss due to heating.
What is a renewable energy resource?
An energy source which can be replenished as it is being used up.
Give four examples of renewable energy resources.
- Wind Energy
- Hydro-Electricity
- Tidal Energy
- Solar Energy
Give an example of a non-renewable energy resource
Fossil fuels (for example coal, oil and gas).
State two disadvantages of using renewable energy resources to generate power
Output often determined by external factors (like wind speed), so supply is uncertain
Generating power through other means is often more efficient and economically
beneficial
Explain the environmental impacts of burning fossil fuels
● Carbon Dioxide contributes to the greenhouse effect, and causes global warming
● Sulphur Dioxide leads to acid rain, which can damage buildings and crops
State three advantages of fossil fuels as an energy resource
Reliable: Not dependent on external factors so can generate power anytime
Can produce large amounts of energy for a given quantity
Still relatively abundant, so cost-effective
State three advantages of nuclear power.
- Produces nuclear waste which is harmful to humans & must be safely stored for centuries.
- Non-Renewable energy source
- Risk of nuclear accidents, which have fatal consequences on humans and the environment
What are some disadvantages of using biofuels?
●When plants are burned or decay they release CO2
●In order to grow biofuels, you need to destroy land destroying natural habitats
