A 853-kg car stopped at an intersection is rear-ended by a 1450-kg truck moving with a speed of 16.0 m/s. If the car was in neutral and its brakes were off, so that the collision is approximately elastic, find the final speed of both vehicles after the collision.

Answer 1

For an elastic collision, both momentum and kinetic energy are conserved.

Conservation of momentum:

m1*v1 + m2*v2 = m1*v1f + m2*v2f

where m1 and m2 are the mass of the car and truck, v1 and v2 are the initial speeds of mass 1 and mass 2, and v1f and v2f are the final speed of mass one and mass 2

Conservation of kinetic energy:
1/2*m1*v1^2 + 1/2*m2*v2^2 =1/2*m1*v1f^2 + 1/2*m2*v2f^2

Insert values, and use algebra to solve for v1f and v2f