1. Warm up 1. a 30 kg child is on a slide (inclined plane) which is at a 55 degree angle with the ground. A. Draw a Free body Diagram of the situation B. If it is a frictionless slide, what is the acceleration of the child down the slide? C. What is the normal force of the slide on the child? D. If the slide is in the real world, and the child slides with a constant velocity, what is the coefficient of friction between the child and the slide?

2. Uniform circular motion Uniform circular motion Motion in a circle Acceleration is the change in what? –___________ Force = mass * ___________ If something is turning in a circle, with constant speed is it accelerating? –___________ If something is turning in a circle, with constant speed, is a force acting on it?

3. What direction is this force going in? –___________ What causes this force? –___________ What would we call this force? –__________ _____________

4. Centripetal acceleration a c = v 2 / r – a c = centripetal acceleration – v = velocity – r = radius of the circle

5. v = change in position / time. For a complete circle, that will be circumference divided by the time it takes to go around the circle (the period)‏ – V = 2*pi*r / T Pi = 3.14152..... r = radius T = time of one revolution

6. Example 1

7. Centripetal Force F = mass * Acceleration –Use a c for the acceleration Centripetal force (F c ) –F c = m*a c = m*[v 2 /r]

8. Example Problem 2

9. Centrifugal force Is a MYTH, it is not a REAL force Do NOT use the term “Centrifugal force” in this classroom please.

10. Homework P 170 (12, 26, 49, 50, 52)‏