1. Uniform Circular Motion
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2. Uniform Circular Motion
Constant speed
Constant radius
Continuous acceleration of a constant magnitude directed radially inward (toward the center)
Continuous net force directed radially inward

3. Like here….
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4. What affects the magnitude of the Net Force?

5. UCM Lab
What is the mathematical relationship between net centripetal force (N) and speed(m/s) for an object undergoing UCM?
Consider: If the independent variable is zero, should the dependent variable be zero?

6. PLQ

7. UCM Thought Experiments
What is the mathematical relationship between net centripetal force (N) and mass (kg) for an object undergoing UCM? (Keep the radius and speed constant)
Consider: If the independent variable is zero, should the dependent variable be zero?
What is the mathematical relationship between net centripetal force (N) and radius (m) for an object undergoing UCM? (Keep the speed and mass constant)

8. UCM Thought Experiments
SFc SFc mass radius

9. Understanding the Lab
What would happen to the net centripetal force if speed doubles but the radius and mass stay constant?
What would happen to the net centripetal force if we keep speed and mass constant, but double the radius?
What would happen to the net centripetal force if we keep speed and radius constant, but double the mass?

10. So…..
If SF = ma
And
SFc = mS2/r
Then ac = ?

11. Equations for UCM
S=2pr/T
ac = S2/r
SFc = m(S2/r)

12. Ex 1
The blades of a blender are 3.0 cm long. The blender spins at a maximum rate of 80 revolutions per second. Determine the speed and acceleration of the tips of the blades.

13. Ex 2
A 20.0 kg child rides on the edge of a 10.0 m diameter carrousel that makes one revolution every 8.00 seconds. Compute the net force acting on the child. What is the direction of that force? If the child was standing on the deck of the carrousel, what type of force would provide the net force?

14. Freebody
In pairs, complete FreeBody Exercise #10 Copy the problem description and the completed diagram into your notes. Be sure to note any forces that balance

15. ac vs speed

16. Understanding the Investigation
What happened to the centripetal acceleration when the speed doubled?