1. Unit: Rotation I.Coordinates:  = s/R,  = v t /R,  = a t /R II.Kinematics: same form, new variables III.Energy: A.Moment of Inertia (rotational mass): I =  mr 2 B.Rotational Kinetic Energy: K = (1/2)I  2 C.Rolling Bodies: only the type of shape matters IV.Torque (rotational force):  = rFsin  V.Angular Momentum: A.L = rpsin  = I  B.  t =  L C.Conservation today

3. A wheel is fixed to the axle of a motor. If the motor is placed on the ice and the motor begins to turn the wheel and axle, what happens to the motor? a) It begins to turn the same direction, with the same speed. b) It begins to turn the opposite direction, with the same speed. c) It falls over. d) It does not turn (L is not conserved because of the motor). e) None of the above. motor axle wheel

4. The earth travels around the sun in an elliptical pattern. When is the earth travelling at the greatest speed? a) When it is closest to the sun. b) When it is farthest from the sun. c) Between the closest and farthest positions. d) The earth travels at a constant speed.

5. A long pole is free to rotate about its center. A paddle is attached to the end of the pole and you wish to get it moving fast by throwing a ball at the paddle. Should you throw a sticky ball or a bouncy ball?

6. The mass of the earth is about 6x10 24 kg. It has a radius of 6,400km and rotates at 2300rad/s. If the entire population of 6 billion people (with an average mass of 80kg) were to begin running, which way must we run to stop the earth?

7. The two balls (each 3kg and 0.2m in radius) are shown as seen from above. The blue ball is initially moving 3m/s and collides with (and sticks to) the stationary red ball. Conceptually, what happens (more than one answer might be correct)? a)The blue ball stops. b)The balls both spin around each other. c)The balls move in the x direction. d)The balls move in a straight line that is not in the x direction. e)The balls move in a curved path.

8. A toy cannon is fixed onto a 6m-diameter merry-go-round at one half the radius. When the cannon is fired, the merry-go-round begins to rotate with an angular momentum of 150 kg*m 2 /s 2. Given that the cannonball is 400g, what is the exit speed of the ball? cannon

9. The following system consists of two wheels (red and blue). Each wheel is mounted to an axle which contains its own motor. The two axles spin within sleeves that are firmly bolted together. The system is placed in outer space, with the red wheel initially spinning. How does the system respond when the motor begins to spin the blue wheel? a) It rotates the opposite direction about the blue wheel’s axis. b) It rotates the opposite direction about the red wheel’s axis. c) It rotates about an axis coming out of the screen. d) It breaks apart. e) It does nothing.