P1 - Conservation And Disspation Of Energy Flashcards
What is chemical energy and how does it transfer energy
Chemical energy stores include food, fuels, or chemicals found in batteries. (Energy is transferred during chemical reactions.)
Name as many energy stones.
-Magnetic
-Internal (thermal)
-chemical
-kintetic
-electrostatic
-gravitational potential
-nuclear
- Elastic potential
What is thermal energy
The energy a substance has because of its temperature.
What is kinetic energy
The energy an object has because it is moving.
What is gravitational potential energy?
Energy stoned in an object because of its position.
Describe the changes to the energy store when a torch is switched on. (4)
- Chemical energy store in battery
- electrical current in wires
- energy transferred to the surroundings
- light waves & increase in the thermal energy stare of surroundings
What is the conservation of energy?
- Energy cannot be created nor destroyed; only transferred
What is a closed system?
- System where no energy transfers take place out of or into the energy stores of the system.
Describe the changes to the energy stores in a system.
Energy can transferred between energy stones within a closed system
The total energy of a system is always the same (before. & after, any such changes.
Why is the conservation of energy A very important idea?
? IDEK
What does work mean in science?
Work is done on an object when a force makes the object move.
How is work and energy related?
Because , energy transferred = work done
What happens to work done to overcome friction?
Work done to overcome friction is transferred as energy to the thermal energy stores of the object that rubs together and to the surroundings
What at happens to the gravitational potential energy store of an object when it moves up or down.
Gravitational potential energy stone of an object increases when it moves and decreases when it moves down
Why does an object moving up has an increase in its gravitational potential energy?
Because work is done on it to overcome the gravitational force.
Why is in easier to lift an object on the moon than on the earth.
Because the gravitational field strength on the moon is lower than on earth
What does the amount of energy in kinetic energy store depend on.
The energy in the kinetic energy store of a moving object depends on its mass and speed.
What is the elastic potential energy store
The energy stored in an elastic object when work is done on the object.
What is useful energy?
Useful energy = energy transferred to where it’s wanted in the way that is wanted.
What’s wasted energy?
Wasted energy = energy that’s not usefully transferred.
What eventually happens to wasted energy?
Wasted energy is eventually transferred to the surroundings.
Is energy still as useful after it is used?
As energy dissipates (spreads out) , it becomes less useful.
What is the maximum efficiency of any transfer.?
100%
How do machines waste energy?
Machines waste energy because of friction between their moving parts, air resistance, electrical resistance and noise.
How can energy transfers be made more efficient.
Machines can be made more efficient by reducing the energy they waste. For example, lubrication is used to reduce friction between moving parts.
How is energy supplied to your home?
Supplied by electricity, gas and oil.
State the useful & wasted energy in a hairdryer.
useful energy = Kinetic energy of the air driven by the fan
wasted energy = sound of the fan motor (sound energy) & heating the hairdryer itself
Why are electrical appliances so useful?
Electrical appliances can transfer energy in the form of useful energy at the flick of a switch.
What are most everyday electrical appliances are used for?
Includes hearing, lighting, making objects move (using an electric motor, and producing sound & visual images.
How to choose an electric appliance for a particular job,
Choose an electric appliance designed for a particular purpose and wastes as little energy as possible.
What is meant by power?
Power is the rate of transfer of energy.
What is meant by efficiency?
Efficiency =
Useful output energy transferred by device(joules)/ total input energy supplied to the device.
