How to hit a baseball or softball further?

Question

I have this idea. Would wearing a weighted backpack help a batter hit a baseball or a softball further? I thought of this because I can accurately hit baseballs and softballs but my problem is that I cannot hit them as far as I would like to. I doubt any adult amateur league has any rules against this because it isn't a tactic likely to be encountered during competition.

It would work like this. After the ball is hit I would drop the bat and quickly remove the backpack and drop it as I ran the bases. But first would it work?

I am a 5'8" 54 year old male weighing 175 lbs with average strength. I believe I should be able to accurately swing with 20 - 30 lbs on my back. What are your thoughts from a physics perspective? And from an ethical perspective? Is this cheating?

Answer 1

No, this will not improve your hitting distance

Yes, it is true that if two objects collide — at least partially elastically — and one one object is heavier than the other, then the heavier it is, the faster this will propel the lighter object.

No, this does not have any relevance here.

At the moment of impact between the bat and the ball, your hands and body are not part of that system. The bat has momentum and inertia; you do not. Your arms have momentum, yes, but your wrists are too flimsy and weak to be able to handle the force that would be needed to transfer any of that momentum from your arms, through the bat, to the ball.

This in turn means that any backpack you wear will not be part of that event. It is entirely disconnected from the bat and the ball at the moment of impact.

So the only thing that matters to you_(*) is how much momentum/inertia you can impart on the bat. Does a backpack help you there?

The thing is that you are standing firmly rooted on the ground. Unless your stance is really bad, you can easily withstand the recoil that you experience when accelerating the bat. In a way, you can say that you have an equivalent of that backpack hat you proposed. Only that this backpack is instead attached to your feet, and it is named planet Earth (or more apt: Terra firma).

_{(*) ...apart from the usual stuff, such as: hit the ball, get the right angle, et cetera.}

Answer 2

First, imagine this situation. A car hits an empty garbage can and sends it flying. Would it make any difference if the car had an extra 100 pounds of weight in the trunk? No, the car is already so much more massive than the garbage can that any extra weight makes no difference, except to possibly slow down the car's acceleration, resulting in a lower speed impact.

There are three aspects of a swing that affect how far a hit ball will travel:

1. The speed of the bat,
2. The direction the bat is traveling at impact, and
3. The location of the impact on the ball.

None of these will be helped by the backpack idea. The only effect will be on the speed of the bat. A swing consists of the combined motions of the leg muscles twisting the hips, the abdominal muscles twisting the torso, and the arm muscles swinging bat. You want your upper body rotating with speed and a weighted backpack will only slow you down or throw you off balance.

Without having seen your swing, I can only guess at what would help. But, one way that increases the distance the ball travels (using points 2 and 3, above) is to swing the bat so that the impact occurs while the bat is moving with a downward slope. This has two effects: it makes it less likely that you hit the very bottom of the ball, resulting in a pop up, and it puts backspin on the ball. This backspin gives the ball lift through the Magnus effect. It's the same thing that makes a curveball move sideways due to the horizontal spin. This lift will make line drives and fly balls carry further than if they had no spin for top spin.

Here's some further reading about batting coaches changing players' swings to turn them into long ball hitters: Why MLB hitters are suddenly obsessed with launch angles - Washington Post

Here, however, the batters are swinging up on the ball to get it in the air with power. This makes the location of the impact on the ball more important, as they only have the lower half of the ball to aim at. Too low an impact means a pop-up. Just below the center of the ball gives a good launch angle, speed, and backspin to carry the ball far.