Q8: Prb 7 - What is the velocity of the car, in meters per second, just after it hits a 165 kg deer initially running at 14 m/s in the same direction? Assume the deer remains on the car.

Question

Consider a 915 kg car initially moving at 31 m/s.

Answer 1

This is an inelastic collision so you can use the conservation of momentum, but not the conservation of energy. Remember momentum is a vector so this is a vector equation. The direction should give positive and negative signs. If we choose the direction the car is traveling as positive the deer will also travel in the positive direction.

p_total = p_car + p_deer = p_total = (915 kg)(31 m/s) + (165 kg)(14 m/s) = (915 kg + 165 kg) v_f

vf = ((915 kg)(31 m/s) + (165 kg)(14 m/s))/(915 kg + 165 kg) ≈ 28.4 m/s