Mechanical equivalent of heat. When you catch a fast-moving object such as a baseball with bare hands, your hands will feel warm immediately after the catch. Suppose a baseball (m = 0.22 kg) moving at 30 m/s (about 60 mi/h) is caught in one hand. How much will the temperature of the surface of your skin increase? Assume the heating is limited to a 1-mm thick layer of skin and all the initial kinetic energy of the ball is converted to heat.