1. The problem statement, all variables and given/known data Two students sit on opposite ends of a sled 6 m long initially at rest on frictionless ice. Each student has a mass of 50 kg; the sled’s mass is 40 kg. The student at one end slides a 2-kg object on the sled across to the other at a uniform speed of 5 m/s relative to the sled (the object moves friction free on the sled). (a) What is the sled’s speed relative to the ice before and after the second student catches the object? (b) Over what distance does the sled move while the object slides across? (c) Over what distance does the centre of mass move while the object slides across? 2. Relevant equations ΣPi = ΣPf xcm = (1/Σmi) Σ(mixi) x-horizontal right = positive 3. The attempt at a solution a) Sled’s speed relative to the ice: ΣPi = ΣPf 0 = 2.0(5) - 40v ( v = velocity of sled with respect to inertial frame) v= -0.25 vs/i = -0.25 -5 = -5.25 After: 0m/s b) Taking the center of the sled as (0,0) xcm = [2.0(-3)+50(-3)+50(3)+40(0)] / (2.0+50+50+40) = -0.0423m xcm = [2.0(3) + 40d] / (142) = -0.0423m d = -0.3m which means the sled moves 0.3m to the left c) Since ΣPi = 0, ΣPf = CM x v = 0 thus CM does not move at all so d = 0 Is my answers correct?