Question

A car of mass 950 kg travelling north at 50 km/h collides with a car of mass 1350 kg going south at 45 km/h in a completely inelastic collision (i.e. they stick together). Determine the velocity of the car/car combination immediately after the collision. (North is the positive direction and south is the negative direction.)

km/h

Answer 1

Given that -

m1 = 950 kg, v1 = +50 km/h (take north direction as positive)

m2 = 1350 kg, v2 = -45 km/h (south direction is negative)

let the final velocity of the combination be V m/s.

now, apply conservation of momentum -

m1*v1 + m2*v2 = (m1+m2)*V

=> 950*50 + 1350*(-45) = (950+1350)*V

=> -13250 = 2300 * V

=> V = -13250 / 2300 = -5.76 m/s

Therefore, final velocity of the combination shall be 5.76 m/s in the south direction. (negative sign shows the south direction.)