1. Centripetal Acceleration Centripetal Force
Circular Motion 2
Centripetal Acceleration
Centripetal Force

2. Do Now Force Fg exists between two masses. What happens to Fg if you…
Double both masses
Double the radius
Triple one mass, double the other, and decrease the radius by ½ r m1 m2 Fg

3. Practice- Circular Motion 1B C A
0.32 s, 9.8 m/s, Yes- changing direction
5 s, 15.9 m
10 s, 0.3 m/s

4. Uniform Circular Motion
Definition: An object that moves in a circular path at constant speed.
Question:
If an object undergoing UCM speed remains constant, does that mean that its velocity is constant?

5. Uniform Circular Motion
Definition: An object that moves in a circular path at constant speed.
Fill in the Blank:
If there is a change in velocity, there must be an ______________.

6. petal- “Walking towards”
Centripetal
centri- “Center”
petal- “Walking towards” V

7. Centripetal Acceleration
An object moving in UCM undergoes a change in velocity. Therefore, that object is accelerating.
a c = v 2 r V ac
ac = centripetal acceleration
v = tangential velocity
r = radius of the circle or arc

8. Centripetal Acceleration
An object moving in UCM undergoes a change in velocity. Therefore, that object is accelerating.
a c = v 2 r = 4 π 2 r T 2 V ac
ac = centripetal acceleration
v = tangential velocity
r = radius of the circle or arc

9. This force always acts towards the center of the circle.
Centripetal Force
The centripetal force is the net force that keeps an object moving in UCM.
This force always acts towards the center of the circle. V Fc
F c =m a c
Fc = centripetal force
m = mass
ac = centripetal acceleration

10. This force always acts towards the center of the circle.
Centripetal Force
The centripetal force is the net force that keeps an object moving in UCM.
This force always acts towards the center of the circle. V Fc
F c =m a c = mv 2 r
Fc= centripetal force
m=mass
ac= centripetal acceleration
v= velocity of the object
r= radius of the circle or arc

13. Question: Fc ac What are some examples of a centripetal force? V
Remember:
The centripetal force is the net force that keeps an object moving in UCM.
This force always acts towards the center of the circle.

14. Types of Centripetal Forces
Friction
Tension
Gravity
Remember:
The centripetal force is the net force that keeps an object moving in UCM.
This force always acts towards the center of the circle.

15. Example 1
A 2000kg car moving at a constant speed of 25m/s takes a turn around a circle with a radius of 200m.
What is the centripetal acceleration of the car?
What is the net force acting on the car?
What is the frictional force acting on the car?

16. Example 2
In an experiment, a 0.3kg rubber stopper is attached to one end of a string. A student whirls the stopper overhead in a horizontal circle with a radius of 0.5 meters. The stopper completes 20 revolutions in 15 seconds.
What is the acceleration of the stopper?
What is the tension in the string?

17. Circular Motion Lab

18. Extended Learning (optional)
Centripetal vs. Centrifugal

19. Centripetal vs. Centrifugal
Centripetal force is the “center-seeking” force that keeps an object moving in a circle. Centrifugal force is the “imaginary” outward “force” felt due to an object’s inertia as it moves in a circle.