Energy

"is the capacity to do work"

measured in Joules (J) (pronounced like jewels)

comes in many different forms/types

CANNOT be negative

For this unit, we will focus on 2 types of energy (with an honorable mention for a third type)

The two types we will look at are kinetic energy and gravitational potential energy

is the energy of motion

anything that is moving (has a velocity) has kinetic energy

is represented by the letter K (sometimes  $KE$   or  $E_K$  )

 $K\ =\ \frac{1}{2}mv^2$  

measured in Joules (J)

is energy stored in an object (it COULD do work)

measured in Joules (J)

can come from many different kinds of energy

Examples: stored electricity, stored chemical energy in batteries, etc

 represented by  $U$  

energy stored in an object due to its distance from the Earth

lifting an object gives it the POTENTIAL to fall back down

represented by  $U_g$  

measured in Joules (J)

 $U_{g_{ }}=mgh$  

m = mass; g = 9.8; h = height off the ground

 $K=\frac{1}{2}mv^2$                        $U_g=mgh$  

kinetic energy is associated with movement (velocity)

gravitational potential energy is associated with position (height)

All energy is measured in Joules (J)

energy CANNOT be negative

change is energy CAN be negative