TOPIC 3 - CONSERVATION OF ENERGY Flashcards
What is GPE?
gravitational potential energy is energy stored in because of an object’s position in a gravitational field. When object moves upwards, stores more GPE
What is KE?
kinetic energy is energ stored in moving objects
Calculating KE?
0.5 x mass x velocity^2
Calculating GPE?
mass x g x height
What affects GPE
- mass of object
- strength of gravity
- how far object moves up
What affects KE
- mass
- speed
What is conservation of energy?
Energy cannot be created or destroyed, only transferred between stores. Total energy transferred by system = energy inputted into system.
What happens in a closed system of energy?
there can be energy transferse but no net change to total energy in that system.
How is energy dissipated?
Energy dissipates when energy is transferred as heat energy, then transferred to surroundings, often caused by friction. This is wasted energy.
How is wasted energy reduced?
- Lubrication reduces friciton on parts that rub together, reducing dissipation of heat energy.
- Insulation prevents dissipation of wanted heat.
How can you keep a building warm?
- Build house out of insulating material e.g. straw bale
- Build a cavity wall - 2 walls with gap between them. Thickness of material affects the rate which energy is transferred through material. Cavity wall increases its thickness, decreasing rate of energy transfer. The air between wall is an insulator so less energy escapes.
What is efficiency
How good a machine is at transferring energy into useful forms
How to calculate efficiency
Efficiency = useful energy transferred by device/total energy supplied to device
number between 0-1
How to increase efficiency
- Reducing friction
- Reducing electrical resistance
- Reducing air resistance
- Reducing noise
What is a renewable energy source
source that replenishes faster than being used
WHat is non renewable energy source
source that is used quicker than made
Name some non-renewable resources
- Fossil fuels
- Natural gases
- Nuclear fuels
Name some renewable resources
- Solar energy
- Hydroelectricity
- Wind turbines
- Tidal power
- Bio-fuels
Advantages + disadvantages of fossil fuels
+ Easy to store so used in vehicles and engines
- Produces CO2
Advantages + disadvantages of natural gases
+ Burning these emit less CO2 than other fossil fuels
Advantages + disadvantages of nuclear fuels
+ Nuclear power stations don’t emit CO2
- Waste that they produce is radioactive and expensive to dispose of safely
- Consequence of power station breaking can be catastrophic
Advantages + disadvantages of solar energy
+ Renewable
- not available at all times, only when sunny
Advantages + disadvantages of hydroelectricity
+ available at all times
Advantages + disadvantages of wind turbines
+ renewable
- wind conditions have to be not too slow or fast
- spoils landscape
Advantages + disadvantages of tidal power
+ time it is available is predictable
+ renewable
- not available at all times
What are bio-fuels
Producing energy by burning animal wastes/plants
Advantages + disadvantages of bio-fuels
+ said to be carbon-neutral because they release same amount of CO2 they took from atmosphere when plants grew.
- Not completely carbon neutral as energy is required in other processes e.g. transport
