Energy Stores and Transfers

Flashcards about energy stores and transfers.

What do chemical energy stores include?

Fuels, foods, or the chemicals found in batteries.

What does kinetic energy store describe?

Energy an object has because it is moving.

What do gravitational potential energy stores describe?

Energy stored in an object because of its position.

What do elastic potential energy stores describe?

Energy stored in a springy object when you stretch or squash it.

What do thermal energy stores describe?

Energy a substance has because of its temperature.

When an object is thrown into the air, what happens to its speed?

The object slows down as it goes up.

When an object starts to fall freely, what force causes it to speed up?

The force of gravity acting on the object.

When a roller coaster climbs an incline, some energy is transferred to the thermal energy store of the surrounding by…

Air resistance and friction, and some energy is transferred by sound waves.

What is a closed system?

A system that experiences no net change in its total energy when energy transfers occur within it

What is a system?

An object or a group of objects.

What is conserved?

Energy cannot be created or destroyed.

During bungee jumping, when the rope is slack, what energy transfer occurs as the jumper accelerates downward?

Energy is transferred from the gravitational potential energy store to the kinetic energy store.

During bungee jumping, when the rope tightens, what happens to the jumper's kinetic energy and the rope's elastic potential energy?

The jumper's kinetic energy store decreases and the rope's elastic potential energy store increases.

During bungee jumping, after the rope recoils and the jumper is pulled back up, bungee jumper's gravitational potential energy store does what?

The bungee jumper's gravitational potential energy store increases throughout the ascent.

When you apply a force to move something, what does the work you do cause?

The work you do causes a transfer of energy.

Where is work done transferred to overcome friction?

Mainly transferred to thermal energy stores by heating.

When an object is moved upwards, the energy in its gravitational potential energy store increases, but what is this increase equal to?

The increase is equal to the work done on it by the lifting force to overcome the gravitational force on the object.

The work done when an object moves up or down depends on what two things?

How far it is moved vertically (change of height) and its weight.

What does dissipated mean?

Spreads out.

Where is wasted energy dissipated?

Wasted energy is dissipated to the surroundings.

What happens to useful energy eventually?

Useful energy is eventually transferred to the surroundings too.

What is input energy?

The energy supplied to the device.

What is useful output energy?

Useful energy transferred by the device.

What can no device be more than 100%?

Efficiency limits.

What supply is vital because you use electrical for so many purposes every day?

Electricity supply.

How is the power of a lift motor related to the speed at which it moves a load?

The more powerful the lift motor is, the faster it moves a particular load.

What is input power?

The energy per second supplied to it.

What is output power?

The useful energy per second transferred by it.