A truck drives to a rock quarry at a speed of 20 m/s. The truck takes on a load of rocks, which doubles its mass, and leaves at the same speed of 20 m/s. Quantitatively compare the kinetic energy of the truck as it left the quarry with its kinetic energy on the way to the quarry. Explain your answer.

Boxing gloves are padded to lessen the force of a blow. (a) calculate the force exerted by a boxing glove on an opponent’s face, if the glove and face compress 7.50 cm during a blow in which the 7.00-kg arm and glove are brought to rest from an initial speed of 10.0 m/s. (b) calculate the force exerted by an identical blow in the gory old days when no gloves were used and the knuckles and face would compress only 2.00 cm. (c) discuss the magnitude of the force with glove on. does it seem high enough to cause damage even though it is lower than the force with no glove?