If she walks at 3 mi/hr, find the minimum speed at which she must row so that the quickest way to the restaurant is to row directly (with no walking)?

Abatter hits a 0.140-kg baseball that was approaching him at 30 m/s and, as a result, the ball leaves the bat at 40 m/s in the reverse of its original direction. the ball remains in contact with the bat for 2.0 ms. what is the magnitude of the average force exerted by the bat on the ball?