Question

A beagle sits on the left end of a stationary raft in still water, as shown. The beagle gets up, walks to the other end of the raft, and sits back down. The beagle and the raft have the same mass. Which of the following statements is true? (You should neglect any drag effects due to the water.)

A) The raft moved in the +x direction while the beagle was walking.

B) The raft moved in the -x direction while the beagle was walking.

C) The raft started moving in the +x direction after the beagle sits back down.

D) The raft started moving in the -x direction after the beagle sits back down.

E) The raft did not move from its original location at any time.

Answer 1

The raft starts moving in the +x direction after the beagle sits back down.

Step-by-step explanation:

The answer is option C. When the beagle walks from one end of the raft to the other and sits back down, the raft starts moving in the +x direction. This is known as the conservation of momentum. The total momentum of the system (beagle + raft) remains constant. Since the masses of the beagle and the raft are equal, the same magnitude of momentum is transferred from the beagle to the raft, causing it to move in the opposite direction.