1. A lab based introduction
Circular motion
A lab based introduction

2. Key vocab Revolving: moving in a circle around something
Earth around the sun
Rotating: Spinning around an axis
The earth spins every 24 hours

3. Key vocab pt 2 Time: how long something takes to happen. (s)
Period: how long something takes to happen once. A reoccurring event. (s)
Frequency: how many times per second something happens. (1/s) or (hz)

4. Period, frequency or time? A moving around the classroom game
What is it?
Period, frequency or time?
A moving around the classroom game

5. It takes 3 hours to run a marathon
It takes about a minute to run each lap during a mile run
An engine idles at around 1000 rpm

6. The earth rotates 1 time per 24 hours
Same game
The earth rotates 1 time per 24 hours
The earth takes 24 hours to complete a rotation
The earth rotated for 24 hours

7. Vocab.
What is velocity?

8. *Disco ball spot activity*
Vocab
*Disco ball spot activity*

9. Big picture For an object moving in circles… Velocity=d/t
V=2πr/T T means period (s)
V=2πr*f f means frequency (1/s)

10. Forces involved in circular motion!
…What does a force do again?
What is acceleration?
What is the unit of force?
…if a object moving in a circle is moving at a constant rate is there even a force involved?

11. Intro to lab
*explain set up, data collection and materials involved*

12. Lab question 1
As you increase the mass on the center hanger what happens to the velocity of the rotating object.
Graph at least 3 points. Do 2 trials per point.
You have 10 minutes.

13. Lab question 1
If forces cause acceleration, what acceleration does this mass cause?’
Based on your graph which is more correct?
F α V
F α 1/V

14. Lab Question 2
As you increase the mass on the revolving mass, what happens to the speed it’s traveling at?
Graph at least 3 points and do 2 trials per data point.

15. Lab question 2
As the spinning mass increases the without changing the force it will spin slower.
The faster something spins the more force it requires to keep moving in the same circle.
With this in mind which is more correct?
Circular force α m*v^2
Circular force α v^2/m

16. Lab question 3
If something is falling at a constant rate it is still exerting a constant force.
Spin your mass and then just hold still and allow the center mass to fall at a roughly constant rate. What happens to the velocity?
Do the experiment several times. Graph what radius (y) versus velocity (x) looks like.

17. If the radius increasing results in a slower spin while force is constant then F α v^2/m

18. Summary
From all your data we can combine these and we find F centripetal= mv^2/r

19. That centripetal thing…
Centrifugal force is not a thing. it comes from inertia.
Centripetal force keeps things going in circles. It’s directed towards the center of the circle.