1. Uniform Circular Motion

2. What we want to know… What is uniform circular motion?
How do you define centripetal acceleration?
What is the difference between a centripetal and centrifugal force?
How do you calculate the force on an object in circular motion?

3. Circular Motion
Circular motion is experienced by any object that revolves around a single axis.

4. Uniform Circular Motion
____ T
v average =
r = radius
T = time to travel once around the circle (period)
Objects further from the center have a greater tangential velocity.
*Draw the circle to the left*

5. Centripetal Force

6. Uniform Circular Motion
“v” is called the
tangential velocity
since its direction
is tangent to the circle
In Uniform Circular Motion (UCM), the velocity’s magnitude does not change. There is no “tangential acceleration.”
“If I were to let go of this when the weight was directly in front of me, which direction would it go?”

7. aavg = vf - vi t Δv Δt = Acceleration Acceleration…
Velocity , change in velocity (Dv), and acceleration are all vectors…
Based on the equation, acceleration due to changing direction will be in the same direction as Dv
aavg =
vf - vi t Δv Δt =

8. Acceleration and Direction...
Change in velocity…
Direction of acceleration is toward the center of the curve
                                       

9. Centripetal Acceleration
Centripetal Acceleration – “Center Seeking”
Acceleration directed toward center of the circle
“Real” acceleration
Copy the equation to
the right (I can’t make it
blue for some reason)
Centrifugal Acceleration – “Away from Center”
“Virtual Acceleration”… an illusion
Don’t use the “F” word

10. Centripetal Acceleration
Newton’s First Law
"... objects in motion tend to stay in motion with the same speed and the same direction unless acted upon by an unbalanced force."

11. Centripetal Force F = mac Newton’s Second Law Centripetal Force
What you feel is actually the force pushing or pulling you toward the center of the circle
a rope, tire friction, the side of the car, etc..

12. Centripetal Force Centripetal Force = Force of Friction
                    
                              
                       
As a car makes a turn, the force of friction acting upon the turned wheels of the car provide the centripetal force required for circular motion.
As a bucket of water is tied to a string and spun in a circle, the force of tension acting upon the bucket provides the centripetal force required for circular motion.
As the moon orbits the Earth, the force of gravity acting upon the moon provides the centripetal force required for circular motion.
Centripetal Force =
Force of Friction
Centripetal Force =
Force of Tension
Centripetal Force =
Force of Gravity

13. End of PowerPoint/ Notes
Complete the practice worksheet