Jack and Jill are standing on a crate at rest on the frictionless, horizontal surface of a frozen pond. Jack has a mass of 75.2kg, Jill has a mass of 46.0kg , and the crate has a mass of 15.9kg . They remember that they must fetch a pail of water, so each jumps horizontally from the top of the crate. Just after each jumps, that person is moving away from the crate with a speed of 3.80m/s relative to the crate.
a) What is the final speed of the crate if both Jack and Jill jump simultaneously and in the same direction? (Hint: Use an inertial coordinate system attached to the ground.)
b) What is the final speed of the crate if Jack jumps first and then a few seconds later Jill jumps in the same direction?
c) What is the final speed of the crate if Jill jumps first and then Jack, again in the same direction?