Center of Percussion A baseball hat rests on a frictionless, horizontal surface. The bat has a length of 0.900 m, a mass of 0.800 kg, and its center of mass is 0.600 m from the handle end of the hat (Fig. 10.64). The moment of inertia of the hat about its center of mass is 0.0530 kg m2 €¢ The bat is struck by a baseball traveling perpendicular to the bat. The impact applies an impulse J = J::F dt at a point a distance x from the handle end of the bat. What must x be so that the handle end of the bat remains at rest as the bat begins to move? [Hint: Consider the motion of the center of mass and the rotation about the center of mass. Find x so that these two motions combine to give v = 0 for the end of the bat just after the collision. Also, note that integration of Eq. (10.29) gives L = f (T) DT (see Problem 10.88).] The point on the bat you have located is called the center of percussion. Hitting a pitched ball at the center of percussion of the bat minimizes the "sting" the batter experiences on the bands.

-0.600 m 0.900 m