A UPS delivery man pushes a 5kg box (A) along a smooth surface where the coefficient of kinetic friction, [µ][/k], is equal to 0.20. The box slides for 1.5m before colliding with a 3kg box (B). The boxes then move together as one unit on a rough surface with [µ][/k]= 0.9 for 0.8m. Determine the initial velocity of the larger box. This problem was on the test that I took today and I'm not sure if I got it correct, or not.
The Attempt at a Solution
v[smooth skid]=2.42m/s =v
v[A][beg skid on rough]=4.56m/s
v[A]=3.86m/s (or something close to that.)
I'm pretty sure I got this one wrong. I wonder how much partial credit I'm going to get...