Energy conservation (5.1)

What is work done?

Work done - product of force and the distance moved in the direction of the force

Work done = force x displacement

Where W is in J

Where F is in N

Where D is in m

Work done = energy transferred

What is the principle of the conservation of energy?

Principle of energy conservation - energy can’t be destroyed or created only created

What are the different types of energy?

Form	What is it
Kinetic	The energy of a moving object
Gravitational potential	The energy something gains when you lift it up, and loses when it falls
Elastic	The energy of a stretched spring or elastic band
Chemical	The energy contained in a chemical substance
Nuclear	The energy contained within the nucleus of an atom
Internal	The energy something has due to its temperature

What is energy dissipation?

When energy is transferred from one store to another not all the energy will be transferred into the store.

This energy is transferred to the surroundings usually in the form of thermal, light or sound

What is efficiency?

Efficiency - the ratio of a systems useful energy output to its total energy output

Efficiency can also be written in terms of power:

What is power?

Power - the rate of energy transfer / work done per unit time

P= E/t = W/t

Where P is in W

Where E and W are in J

Where t is in s 

What is moving power’s relationship with force and velocity? and how can it be derived?

P = Fv

Where P is in W

Where F is in N

Where v is in ms^-1

This equation is only usable when the object has a constant velocity and a constant force with the force and velocity being in the same direction

Derivation

1) Power = work done/time

2) Work done = force x displacement

3) Power = (force x displacement)/t

4) Velocity = displacement/t

5) Power = force x velocity