When cars are equipped with flexible bumpers, they will bounce off each other during low-speed collisions, thus causing less damage. In one such accident, a 1750-kg car traveling to the right at 1.50 m/s collides with a 1450-kg car going to the left at 1.10 m/s. Measurements show that the heavier car’s speed just after the collision was 0.250 m/s in its original direction. Ignore any road friction during the collision. (a) What was the speed of the lighter car just after the collision? (b) Calculate the change in the combined kinetic energy of the two-car system during this collision.

Solution to 22E Step 1 Mass of car A =1750 kg Mass of car B =1450 kg Initial velocity of car A =1.5m/s Initial velocity of car B =-1.10m/s Final velocity of car A=0.250m/s Step 2 (a) Since no external force is acting on the system, according to conservation of momentum, m v +m v =m v’ +m v’ a a b b a a b b v’b= {m va a vb bv’a/ma b v’ =0.338m/s to right b