# Energy

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• Created by: Eesha Dev
• Created on: 07-12-15 18:41

Information on Energy

• Energy is the ability to do work.
• Energy is measured in Joules (J)
• Potential energy is stored energy
• The law of conservation of energy states that energy cannot be created or destroyed.  It can only be transformed from one form or energy to another

Types of Energy

• Kinetic energy
• Sound energy
• Gravitational potential energy
• Elastic potential energy
• Chemical energy
• Electrical energy
• Light energy
• Nuclear energy
• Thermal energy

Mass and Weight

• mass is the amount of "stuff" inside of something. It is measured in kilograms
• weight is the downward force applied by gravity. It will change if you leave Earth. It depends upon the gravitational pull.
• Weight = Mass x Gravitational Pull
• W = mg
• Earth's gravitational pull is 10N/kg

Work Done

The amount of work done is equal to the energy transferred

Use these formulae:

• Work done = force x distance
• W = Fd
• Joules (J) Newtons (N) Meters (m)
• Work = mass x gravitational pull (weight) x distance / height
• W = mgh
• Joules (J) Kilograms (kg) Meters (m)

Power

• power is the work done, or energy transferred, in one second
• it is measured in Watts

Use these formulae:

• Power = Energy / Time
• P = E / t
• Energy = Power x Time
• Time = Energy / Power

Kinetic Energy

There are two things that affect kinetic energy: mass and speed

• the larger the mass, the larger the kinetic energy
• the larger the speed, the larger the kinetic energy
• Kinetic Energy = 1/2 mass x speed
• KE = 1/2 mv
• 2KE = mv
• m = 2KE / v
• v =     2KE/m

Elastic Potential Energy

There are two things that affect EPE:

• the distance the elastic is stretched - extension (x)
• how much force is required to pull it
• the bigger the distance it is pulled, the bigger the force and therefore, the bigger the energy stored in it

The force needed to pull the elastic back depends on how stretchy it is. The stiffer the elastic, the harder it is to pull and the more energy…