the faster the bat travels the farther the ball will go when hit. Players through the years have made studies of lighter bat vs heavier bat. The conclusion is that the speed of the bat is a bigger factor that the size/weight.

when you have a ball traveling at 95+mph u need a fast bat to hit it

It does help the ball travel further. Adjustment of bat speed I think is more important. Swinging a little early to send the ball down the line...swinging late to send the ball to the opposite field. Having strong wrists is very important...Hank Aaron was not built like a linebacker but he had very strong wrists thus better bat speed and control.

this is a question of physics. In general, force = mass x acceleration. Force basically means how hard the ball is hit. the mass of the ball does not change, so the only thing that will affect the distance that a ball goes when hit is the acceleration of the bat when hitting it. The higher the acceleration, the more force is exerted on the ball, which means the ball will go further. If you think in opposite terms, if a hitter bunts the ball, there is practically 0 acceleration, thus resulting in the ball going only 10-15 feet.

i agree with most of the answers, but the accleration means squat if you don't have the muscle to back it up. It also helps to have a really good bat. I like wooden ones, but the popular thing right now is mettle.

Good bat speed allows a player to sit back on a pitcher longer and look at the ball on the way to the plate. Major Leaguers can, generally speaking, wait on a pitchers curve or slider and still be able to get their bat around on a fastball to foul it off and stay alive.