CH. 4 Energyand a little bit of Ch. 5

•4.1 The Nature of Energy•4.2 Conservation of Energy

•5.1 Work

4.1 What is energy?

• Motion needs ____________: Measured in ____________

• Energy Types: electrical- _______- radiant-thermal- sound- nuclear – ________________

Potential Energy

• __________ energy /no motion• When a ________________ is pulled back it has

____________ energy• ___________ potential energy

• food

• ____________ potential energy – Any type of stretched or compressed elastic material

• Clock ____________• Bungee cord

• Gravitational Potential Energy

– Apple hanging from a tree– Depends on __________ of objects– Depends on __________ between objects– Grav.PE=mass x ___________ acceleration x height

•PE=mgh

Kinetic Energy

• When the apple falls off the tree it has– ___________ Energy

• Depends on ___________(v)• Increase in speed results in _____________ ability to do work• Kinetic energy =1/2 x ______(kg) x speed squared

KE=1/2 m ___2

4.2 Conservation of Energy

• Transforming energy:

Light Bulb: ____________ Light thermal

Gasoline: __________ kinetic motion electrical thermal sound

• _____________ Energy= potential + kinetic

The Law of Conservation of Energy

• Energy cannot be created or destroyed, only transformed.

• Mechanical Energy= K.E. + P.E.

• K.E.=P.E.

5.1 Work

• The measure of the _________ over the entire distance covered

• _____________ Force=Motion • Motion=Distance covered• Work= ________ x Distanc W= F x d

– Joules (ENERGY!!)

Power

• The measure at the rate at which work is done

• Power = _______/Time P=W/t– ________/Seconds= Watts

• Power-___________