1. 8.2 Conservation of Energy
How can you find an object’s mechanical energy?
What is the Law of Conservation of Energy?

2. Energy associated with the motion, position, &/or shape of an object
Mechanical Energy
Energy associated with the motion, position, &/or shape of an object

3. The ball’s mechanical energy
TRUE
True or False?
The ball’s mechanical energy
does not change from
Point A to Point B.

4. The ball’s Mechanical Energy does not change, BUT…
22 J
The ball’s Mechanical Energy does not change,
BUT…
the amount of Potential Energy & Kinetic Energy changes.
22 J
Why does the ball’s gravitational PE increase from points A to B?
The ball gets higher!

5. How can you tell that the ball’s kinetic energy is increasing?
The ball is covering more distance in equal time intervals, so its speed must be increasing.

6. Energy TransformationC.
A change of energy from one form to another.
Evaluate the pendulum and ENERGY TRANSFORMATION at positions A,B & C (p. 298) B.

7. Elastic
Potential
energy
Kinetic
energy
Gravitational
Potential
energy
Kinetic
energy
From his running.

8. motion
position
shape
Its kinetic energy is zero
because mechanical energy
equals potential energy plus
kinetic energy.
5.2 J J = 8.7 J
adding together the object’s kinetic energy and potential energy.

9. Law of Conservation of energy
Energy cannot be created or destroyed, only transferred

10. Conserving Energy While You Ride (p.300):
Transformations between potential and kinetic energy occur during a roller coaster ride. How much potential and kinetic energy does the coaster have at each point?

11. Thermal Energy (or Heat Energy)
The total kinetic & potential energy
of the PARTICLES that make an object

12. Whenever a moving object experiences friction, some of its kinetic energy is transformed into thermal energy

13. The total amount of energy before
a transformation is the same as after
a transformation.
cannot be created or destroyed.

14. Create friction & thermal energy
1. Put your hands together.
2. Vigorously rub, & feel the burn
Friction causes
some mechanical energy (ME) to be converted to thermal energy (TE).