A ballet dancer is spinning in the middle of a horizontal frictionless stage. Which of the following things could he change by moving parts of his body or his whole body? (There could be more than one correct choice.)
A) his total kinetic energy
B) the location of his center of mass (or center of gravity)
C) his angular momentum
D) the horizontal component of his linear momentum
E) his rotational kinetic energy
F) his translational kinetic energy
G) his moment of inertia
Question 2
A small but dense 2.0-kg stone is attached to one end of a very light rod that is 1.2 m long. The other end of the rod is attached to a frictionless pivot. The rod is raised until it is vertical, with the stone above the pivot.
The rod is released and the stone moves in a vertical circle with no air resistance. What is the force that the rod exerts on the stone as the stone moves through the bottom of the circle? A) 20 N
B) 40 N
C) 60 N
D) 80 N
E) 100 N