What is ENERGY??

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Energy

Energy is the ability to do work.

Whenever work is done, energy is transformed or transferred from one object to another object.Ex. Using a hammer to put a nail in a piece of wood.

Potential Energy

Potential Energy is the energy an object has because of its position or shape.

Any object that can be stretched or compressed has potential energy called elastic potential energy.

EXAMPLES???

Calculating Potential Energy

PE = mass x free-fall acceleration x height

PE = mgh

Units of Potential Energy = joules (J)

Example

Mass = 65kgHeight = 35mFree-fall acceleration= 9.8 m/s2

What is this objects potential energy?

PE= 65kg x 9.8m/s2 x 35m =22,000 J

Kinetic Energy

Kinetic energy is the energy an object has because it is MOVING.

Example: When an apple is hanging from a tree brand it has potential energy but when the apple falls toward the ground it now has kinetic energy because it is MOVING.

Kinetic energy of an object depends on both the object’s mass and its speed.

Example: A bowling ball does more work than a tennis ball when they are moving the same speed. WHY???

IT HAS MORE MASS!!!!

Calculating Kinetic Energy

KE = ½ x mass x speed squared

In the equation, speed is squared so even a small change in speed will cause a large change in Kinetic Energy.

Example

What is a snowboarder’s kinetic energy if her mass in 50kg and she is going at a speed of 4 m/s?

KE = ½ x 50kg x KE = ½ x 50kg x 16KE = 400 J

Kinetic EnergyAtoms and molecules are always moving so they have kinetic energy.

The faster the particles in a substance are moving, the higher its temperature.

This is because temperature is a measure of the average kinetic energy of the particles in a substance.

Mechanical Energy

Mechanical energy is the amount of work something can do because of its kinetic and potential energies.

ME = kinetic energy + potential energy

An objects mechanical energy can be all kinetic energy, all potential energy, or some of both.

• An object’s mechanical energy remains the same as long as no energy is added.

• If an object’s potential energy increases then it’s kinetic energy much decrease.

• If an object’s potential energy decreases then it’s kinetic energy must increase

Nonmechanical Energy

Nonmechanical energy- forms other than mechanical energy

Such as: Chemical energyNuclear EnergyElectrical EnergyLight Energy