CH 7 Study Guide Circular Motion and Gravitation 1. Angular Meaure a. Angular displacement: i. Definition ii. Units = – conversions between degrees, radians, and revolutions and rotations iii. Positive vs. negative 2. Angular Speed and Velocity a. Compare and contrast speed and velocity b. Equation: c. Units: Conversions of rpm to rad/s => d. Positive vs. negative e. Period and frequency: 3. Uniform Circular Motion ad Centripetal Accleration a. Define UCM – two conditions i. ii. b. In UCM an object has constant tangential speed, but the direction of that speed is always changing meaning the object is accelerating Centripetal Acceleration a. Result of the change in the ________________ of the tangential velocity of an object in UCM b. Equation: c. Units: d. Direction of vector: e. Centripetal Force a. Equation: b. Four forces that supply centripetal force needed for UCM 1. 2. 3. 4. 4. Angular Acceleration a. If an object moves in a circle, but not at the same rate b. Equation: c. Units: d. Positive vs. negative 5. Kepler’s Laws and Earth Satellites a. ID each of Kepler’s three laws b. What is the relation of each of the three laws to the first 4 items listed in this study guide? Practice: 1. Convert 20.0 rad/s to rpm 2. Convert 1500 rpm to rad/s 3. The cutting cord on the end of a weed cutter is 0.16 m long. If the motor rotates at 20 rev/s, what is the angular speed in rad/s and what is the tangential speed of the end of the cord? 4. A 0.300 kg toy car makes 1.5 m diameter circular turns on a table top. The car moves at 1.5 m/s. What is the centripetal acceleration of the car? What is the angular acceleration of the car? What is the centripetal force acting on the car? What is the coefficient of friction between the table top and the car? 5. How many revolutions does a 0.100 m radius wheel make after starting from rest and accelerating at a constant angular acceleration of 2.00 rad/s2 for 10.0 s? What is the final speed of the wheel? 6. The gravitational force between two objects when separated by 2 m is F. The objects are moved to 4 m apart. What is the force between the two at the larger separation? 7. Is the tangential speed of the earth around the sun always the same?