part A
A merry-go-round (MGR) is spinning about a frictionless vertical axle. A student standing beside the rim of the spinning wheel holds a sandbag a few millimeters above the rim of the wheel as it spins underneath. Suddenly, the student drops the sandbag; it hits the rim of the wheel and sticks, and the MGR with the sandbag on its rim ends up turning as a unit. For this action, which of the following statements about the angular momentum of possible systems in this experiment is correct?

1)The angular momentum of the sandbag, about the central axle of the MGR, is constant during this experiment.

2) Neither the angular momentum of the MGR alone, nor of the sandbag alone, nor of the sandbag-MGR system, is constant during this experiment (in each case, the angular momentum is taken about the central axle of the MGR).

3)The angular momentum of the sandbag-MGR system, about the central axle of the MGR, is constant during this action.

4) The angular momentum of the MGR, about its central axle, is constant during this action.

Part B

A student is riding on the edge of a spinning merry-go-round (MGR); he is sitting cross-legged on the MGR edge, facing radially outwards, and holding a sandbag so that if he releases the sandbag it will fall onto the ground just beyond the MGR edge. Suddenly, he releases the sandbag; it falls to the ground where it sticks and thus stops moving. Consider the following statements concerning angular momentum, as measured about the central vertical axle of the merry-go-round, in this experiment. Select all true statements.
Select all true statements. The angular momentum referred to in the statements is measured about the central vertical axle of the merry-go-round.
Select all true statements. The angular momentum referred to in the statements is measured about the central vertical axle of the merry-go-round.
1) The angular momentum of the system consisting of the student and the merry-go-round is constant.
2) The angular momentum of the sandbag is constant.
3) The angular momentum of the system consisting of the sandbag, together with the merry-go-round and the student, is constant.
4) The angular momentum of the student is constant..
5) The angular momentum of the merry-go-round is constant.

Part C

As shown in the figure, a merry-go-round (MGR) is free to spin about a frictionless vertical axle (marked O); the figure is drawn looking down on the MGR. The MGR is initially not spinning. A small cannon (not drawn in the figure) is mounted on the western rim of the MGR; the cannon can be fired in any of the four horizontal directions which are drawn in the figure and labeled as A, B, C, and D (direction A is horizontally South and direction D is horizontally West). Consider the system of cannon, cannonball, and MGR, and consider the angular momentum of this system about the axle O. Initially, all parts of the system are at rest, and “just after firing” the cannonball has just left the barrel of the cannon and is traveling in one of the four labeled directions, but has not yet traveled far enough to have experienced any significant effects from the force of air resistance. For which of the four labeled firing directions will the angular momentum of the system, about the axle O, be constant during the described action?
Image was attached;
1) For only direction D.
2) For only directions B and C.
3) For all four directions.
4) For all directions except D.
5) For none of the four directions.
6) For all directions except A.
7) For all directions except B and C.
8) For only direction A

Part D