physics
posted by help on .
A 910 kg sports car slows down to 6.0 m/s to read a cross street sign. The 1440 kg pickup truck following the sports car fails to see that the sports car has slowed and continues traveling at 17.0 m/s. The pickup slams into the sports car. With what velocity will the two move, if they lock bumpers after the rear end collision? Assume both cars are traveling north and north is the positive direction
I tried find the change in momentum between the two cars then equating that momentum with both mass together and solved for the final velocity but i got it wrong.

M1 = 910kg*6m/s = 5460kgm/s
M2 = 1440kg*17/s = 24480kgm/s
Mt = M1+M2 = 5460+24480 = 29940 kgm/s
Masstot = 910 + 1440 = 2350kg
V = Mt/Masstot = 29940/2350 = 12.74 m/s