WORD SEARCH

How many forms of energy can you find? Can you think of an example for each type of energy?

There are many different types of energy:

thermal

light

sound

elastic

gravitational

kinetic

electrical

chemical

nuclear

Different types of energy

elastic

gravitational

kineticchemical

By the end of the lesson you should be able to:• Explain what kinetic energy depends on• Calculate the kinetic energy of moving objects• Explain what gravitational potential depends on• Calculate the gravitational potential energy of

objects

Gravitational Potential Energyand Kinetic Energy

• When you lift an object up, energy is transferred from your muscles in to gravitational potential energy of the object.

Gravitational potential energy (GPE) is energy stored in an object because of its position in the earths gravitational field.

• Which books have GPE?• Which book has the most GPE?• Which book has the least GPE?

• What would happen to the GPE of book C, if you moved it to the higher shelf?

• Where did this energy come from?

• What would happen to the GPE of book B, if you moved it to the lower shelf?

The amount of gravitational potential energy an object on Earth has depends on its:• Mass• Height above the

ground

What do you think GPE would depend on?

Gravitational potential energy is the energy stored in an object because of its height above ground.

Gravitational potential energy = _____x gravitational field strength x _____

orEp= m x g x h

Ep: the change in gravitational potential energy (unit:___)m: the ____ (unit:______)g: is the gravitational field strength (unit:_____)h: is the change in ______ (unit:______)

Gravitational potential energy is the energy stored in an object because of its height above ground.

Gravitational potential energy = Mass x gravitational field strength x Height

orEp= m x g x h

Ep: the change in gravitational potential energy

(unit: J)m: the mass (unit: kg)g: is the gravitational field strength (unit: N/kg or m/s2)h: is the change in height (unit: m)

Calculate change in GPE, when a 1000kg aeroplane, takes off up to a height of 500m.

change in GPE =mass x change in height x gravitational field

strength (10 N/kg)

A dog of mass 12 kg falls from an aeroplane at a height of 3.4 km. How much gravitational energy does the dog have as it leaves the aeroplane?

(The dog has a parachute and is not harmed during this physics experiment)

Woof! (help!)

Example

On earth g = 10 m/s2

Height = 3.4 km = 3400 m

Mass of dog = 12 kg

Example

On earth g = 10 m/s2

Height = 3.4 km = 3400 m

Mass of dog = 12 kg

GPE of dog = mgh = 12 x 10 x 3400 = 408 000 J

Example

GPE of dog = mgh = 12 x 10 x 3400 = 408 000 J

Just before the dog hits the ground, what has this GPE

turned into?

Example

Kinetic energy

A jaguar A tortoise?or

This jaguar This jaguarorThe kinetic energy depends on… 1.

2.

Which one has the most kinetic energy?

Kinetic energy is the energy an object has due to its motion. It depends on two things:• Mass of the object• Speed of the object

Kinetic energy (KE) = 1 x mass x speed2

2UnitsKE: _____Mass: _____Speed: ____

Kinetic Energy

• A car with a mass of 500 kg is moving at a speed of 12 m/s. How much kinetic energy does it have?

• A car with a mass of 500 kg is moving at a speed of 12 m/s. How much kinetic energy does it have?

KE= ½ x m x speed2

KE=½ x 500 x (122) = 36,000 j

Where is this useful?• Many theme park rides use the transfer of

gravitational potential energy to kinetic energy and kinetic energy to gravitational potential energy.

https://www.youtube.com/watch?v=Ehx1P4adv6I

Texas locomotives accident (1896)

http://sciencewaldegrave.weebly.com/

https://www.youtube.com/watch?v=8H41zbqrwVo