P1 - Conservation and Dissipation of Energy

What are all the ways energy can be transferred by?

heating, waves, electrical current or by a force (mechanical) .

What happens to the energy when an object falls and gains speed?

Gravitation potential energy decreases and its kinetic energy store increases.

What happens to the energy when a ball hits the ground without bouncing back?

Its kinetic energy store decreases. Some or all of its energy is transferred to the surroundings - thermal energy store of the surroundings increases and energy is transferred by sound waves.

What is all the energy stores?

chemical

thermal/internal

gravitational potential

elastic potential

nuclear

electrostatic

magnetic

kinetic

What is the principle of conservation of energy?

Energy cannot be created or destroyed

What does conservation of energy apply to?

all energy changes

What is a closed system?

A system in which no energy transfers can take place out of or into the energy stores of the system

Energy can be transferred in a closed system..

between energy stores. The total energy of the system is always the same

What is the definition of work done?

When a force makes an object move.

What is work done to overcome friction transferred as?

energy to the thermal stores of the objects that rub together and to the surroundings

Does the gravitiational potential energy increase or decrease when an object moves up or down?

When an object moves up - gpe increases
when an object moves down - gpe decreases

Why does gpe increase when it is lifted up?

Work is done to overcome the gravitational force

IS gpe on the moon greater or smaller than on the earth?

The gravitational field strenght on the moon is smaller

What does the energy store in a kinetic object depend on?

its mass and speed

What is elastic potential energy?

energy stored in an elastic object when work is done on an object.

What is Hooke's law?

The extension of a spring is directly proportional to the force applied

What is useful energy?

Energy in the place where it is needed and in the form wanted

What is wasted energy?

Energy that is not useful energy and is transferred in an undesirable pathway

Where is wasted energy eventually transfered to?

To the surroundings, which become warmer

As energy dissipates(spreads out)...

It gets less and less useful

What is input energy?

Energy that is supplied to the device

No energy transfer can be more than...

100% efficient

Why can no energy transfer be more than 100%

You can't get more energy from a machine than you put into it

Why does machines waste energy?

Friction between the moving parts, air resistance, electrical resistance and noise.

How can machines be more efficient?

Reducing the energy they waste. For example, lubrication to remove friction between moving parts.

What supplies most of the energy in your home?

Electricity or gas and or oil

What are some uses of everyday electrical appliances?

heating, lighting, making objects move and producing sounds and images

What is an electrical appliance designed for?

A particular purpose and should waste as little energy as possible.

What is the definition of power?

the rate of the transfer of energy