A boxcar of mass 8700 kg is traveling at 11.0 m/s strikes a second boxcar moving in the same direction at 2.2 m/s. The two stick together and move off with a speed of 4.00 m/s. What is the mass of the second box car? Explain your reasoning.

m = 33833.3 kg

Explanation:

let M be the mass of boxcar 1 and V be the velocity of boxcar 1, let m be the mass of boxcar 2 and v be the velocity of boxcar 2.

from conservation of linear momentum:

M*Vi + m*vi = vf (M + m)

M*Vi - M*vf = m*vf - m*vi

M (Vi - vf) = m (vf - vi)

m = [M (Vi - vf) ] / (vf - vi)

= [ (8700) (11.0 - 4.00) ] / (4.00 - 2.2)

= 33833.3 kg

Therefore, the mass of boxcar 2 is 33833.3.