More damage is done and more life is endangered in a head-on collision of two cars, each traveling at 30 mph, than in a car crashing into a brick wall at 30 mph because: the relative velocity of the head-on collision is the product of the two velocities. the relative velocity of the collision of the wall is absorbed by the wall. the relative velocities are opposite of each other and therefore have a net sum of zero. the relative velocities of the head-on collision are the sum of the two velocities.