This document discusses different forms of mechanical energy including kinetic energy and potential energy. Kinetic energy is the energy of motion and depends on an object's mass and velocity, while potential energy is stored energy that depends on an object's position or state. The document provides examples and equations for calculating kinetic energy (KE=1/2mv^2) and gravitational potential energy (PE=mgh). It also introduces the law of conservation of energy, which states that the total energy in a system remains constant, as energy is transformed between kinetic and potential forms.

1. Chapter 5.2

2. Energy
 The ability to do work
 Any object that has energy has the ability to create
force to do work
 Energy is measured in the same units as work
 Unit – joule(J)

3. Forms of Mechanical Energy
1. Kinetic Energy
 Energy in the form
of motion
Ex) A spinning
bicycle wheel
Ex) Sprinting runners
2. Potential Energy
 Stored Energy –
not moving
Ex) A drawn bow
Ex) A book on the top
shelf
Ex) A stretched
rubber band

4. Potential Energy
 Depends on its
position above the
ground
 The greater the
height, the greater
the PE
 Examples
 Gravitational potential
energy (g)
 Elastic potential
energy

5. Potential Energy
Ep = mgh
Height (m)
Potential Energy (J)
Acceleration
of gravity (m/sec2)
Mass (kg)

6. Kinetic Energy
 The greater the mass
the more KE
 The greater the velocity
the greater the KE
 Here the green particle
is moving twice as fast
as the yellow particle. It
has more kinetic energy
than the yellow one.

7. Kinetic Energy
Ek = ½ mv2
Speed (m/sec)
Kinetic Energy (J)
Mass (kg)

8. Mechanical Energy
 Equals the total amount of KE and PE in a
system
 Mechanical Energy = KE + PE

9. Law of Conservation of Energy
 Energy can never be created nor destroyed its
transformed into another energy

10.  Total energy can never exceed starting energy
(it should always be equal)
 KE converted to PE and back
 Friction slows objects down