Question

A 1,600 kg car traveling north at 10.0 m/s crashes into a 1,400 kg car traveling east at 15 m/s at an unexpectedly icy intersection. The cars lock together as they skid on the ice. What is their speed after the crash?

Answer 1

Use conservation of momentum to get the north and east components of the final velocity, V. Then compute the resultant V, which will be the hypotenuse.

3000*Vy = 1600*10 = 16,000 kg m/s
3000*Vx = 1400*15 = 21,000 kg m/s
Vy = 5.333 m/s
Vx = 7.00 m/s
Speed = sqrt[Vx^2 + Vy^2] = 8.8 m/s
(Friction has been assunmed negligible becasue of the the ice.