Jane and Ochan are sitting in a canoe. Ideally, Ochan wants to know Jane’s

mass, but he won’t tell her. He tricks her into switching positions with him in the canoe.

After the switch, he notices that the canoe moves 2 feet. He knows that his mass is 100 kg.

If the canoe is 12 feet long and has a mass of 40 kg, what is Jane’s mass? (Assume that there

are no external forces on the system).