Using Energy Flashcards
What are the different forms of energy?
- Light
- Heat (thermal)
- Sound
- Kinetic
- Nuclear
- Electrical
- Gravitational Potential
- Elastic Potential
- Chemical
The last three are forms of stored energy
When is energy most useful?
When it can be transfered from one form to another
Energy can be ____________ but it cannot be __________.
Energy can be transfered from one form to another but it cannot be created or destroyed.
This is known as the conservation of energy
What happens when an object falls?
It gains speed and its gravitational potential energy decreases whilst its kinetic energy increases
What type of energy do all objects above the ground have?
Gravitational potential
What does conservation of energy apply to?
All energy changes
What is a machine?
Something that transfers energy from one place to another or from one form to another
What does the energy we get out of a machine consist of?
Useful energy, which is transfered to the place we want in the form we want.
Wasted energy, which is not usefully transfered.
Where will both useful and wasted energy eventually be transfered?
To the surroundings, causing them to heat up
What happens when energy is transfered to the surroundings.
They heat up and the energy spreads out. This makes it more difficult to use for further energy transfers
How is energy often wasted?
Because of friction between moving parts of a machine. The energy warms up the machine and the surroundings.
When might friction be useful?
In the brakes of a bike/car.
The kinetic energy of the vehicle is transfered to heat energy heating the brakes and thus slowing the vehicle.
What is the energy supplied to a machine known as?
The input energy
What do we know about the relationship between the input energy and the output energy?
input energy = useful energy + wasted energy
What makes a machine more efficient?
The less energy a machine wasted, the more efficient it is
Draw a Sankey diagram showing the transfer of 100J electrical input energy to 10J useful light energy and 90J wasted heat energy in an electric lamp.
