1. Do Now Which of the following objects is accelerating: a. A car slowing down. b. A free fall object momentarily stopped at its max height. c. A ball tied to a string, being swung around in circles at a constant speed.

2. Uniform Circular Motion An object which is moving in a circular path with a constant speed is said to be in uniform circular motion. Distance of a circle = circumference d = 2πr (T) Period – time it takes an object to complete one revolution.

3. Kinematics of Uniform Circular Motion Centripetal Acceleration (a c ) : acceleration due to change in direction rather than magnitude of the velocity, always point towards center of the circular path. v a r Circular Motion: Gravitation

4. The velocity vector is tangent to the path of the ball, and points in the direction the ball would move if the string were to break at that instant.

5. 21. A jet airplane is flying in a horizontal circle of radius 500 meters, such that the jet will complete a full circular motion in a time of 25 seconds. What Velocity will the jet experience? (round to 1 decimal)

6. 21. A jet airplane is flying in a horizontal circle of radius 500 meters, such that the jet will complete a full circular motion in a time of 25 seconds. What Centripetal Acceleration will the jet experience? (round to 1 decimal)

7. Centripetal Force (F C ) Anytime an object accelerates centripetally there must be a net force (ΣF) causing a c ΣF C must point towards the center ΣF C can represent –F Tension for a ball or a string –F g for orbit –F fric for car around a circular turn

8. Centripetal Force

9. A clump of dried clay of mass.1 kg sits at the edge of a potter’s wheel of radius 15cm. If the clump slips off when the wheel’s rotation rate reaches 75 rpm (revolutions per minute) a) determine the velocity of the clay (round to 1 decimal).

10. A clump of dried clay of mass.1 kg sits at the edge of a potter’s wheel of radius 15cm. If the clump slips off when the wheel’s rotation rate reaches 75 rpm (revolutions per minute) b.) Determine the Centripetal Force (round to 2 decimals)

11. A clump of dried clay of mass.1 kg sits at the edge of a potter’s wheel of radius 15cm. If the clump slips off when the wheel’s rotation rate reaches 75 rpm (revolutions per minute) c.) Calculate the coefficient of static friction between the clay and the wheel. (used g = 9.8, round to 2 decimals)