1. Do Now:
Miguel is playing with his toy cars and sends one around a circular track.
If the track has a radius of 30 cm and the centripetal force acting on the car is 30 Newtons. What is the work done to go around the track just once?
W = FII x d
W = F

2. Aim: How do we know if an object has energy?
HW: Worksheet

3. Work-Energy Theorem ENERGY is the ability to do WORK
WORK is the release of ENERGY
Therefore:
BOTH have the units of JOULES!

4. Which has more energy? I have two weights of different mass.
Situation 1: Both masses sit on a table
Neither, both have 0 J of energy
Situation 2: Both masses are raised to the ceiling
The larger mass, it has more potential.
Situation 3: The small mass is raised to the ceiling and the large mass is raised 5 cm.
The smaller mass, it has more potential

5. So what does this “Gravitational Potential Energy” depend on?
1. How strong is the field? (g)
2. What is the object’s mass? (m)
3. How high is the object above the surface? (h)
Increase height (WORK IN)  Increases PEG
Decrease height (WORK OUT)  Decrease PEG
*What is the PEG in our 3 situations?

6. How does PE relate to Work?

7. Example #1
An aircraft with a mass of 2.0 x 105 kilograms is flying at an altitude of 3.0 x 103 meters.
What is its gravitational potential energy?
How much work is needed to be done against gravity for the aircraft to reach this altitude?
-5.89 x 109 J

8. Lets play catch…
If I ask you to put a lot of energy into a throw. What is going to be the result?
More speed = More energy
Earlier we dropped two masses from the ceiling…
Which one has more energy? Why?
The larger one, it has more mass

9. What does the energy for an object in motion depend on?
Energy in motion depends on:
Mass & Velocity
This is called Kinetic Energy.
Why does the name make sense?

10. How does KE relate to W?

11. Station Activity
Go to the assigned station and work together on the questions given.

12. Station 1
A 1000 kilogram car starts from rest and attains a velocity of 20 meters per second as it travels a distance of 100 meters.
What is the car’s initial KE?
0 Joules
What is the car’s final KE?
How much work was done on the car?
Joules

13. Station 2
A 1000 kilogram car changes its speed from 20 meters per second to 10 meters per second within 100 meters of travel.
What is the car’s initial KE?
Joules
What is the car’s final KE?
How much work was done on the car?
Joules

14. Summary What the units for energy?
What are the two types of energy an object can have?
What is the equation for each?