Question

Young softball batters are often instructed to “choke-up on the bat” by their coach. In terms of the moment of inertia, what exactly does this accomplish and why is it an advantage to the young batter? Come up with one other real-life example where either increasing or decreasing the moment of inertia becomes an advantage? Clearly describe the example and talk about the variables involved.

Answer 1

First of all, let's first undertand what is choking up on the bat.

In simple terms, it is like moving our hand up on the baseball bat so as to increase the distance between hand grip and the bottom of bat where the ball strikes.

How does it help ??

When a batter hits a ball, he/she tries to rotate the whole body about an axis of rotation. When the hands are far away from the axis of rotation, the moment of inertia will be high and angular velocity will be low.

Here is the equation which relates these

T = Iw

where T is torque, I is moment of inertia, w is angular velocity

Now, when we choke up on the bat, the hand comes close to the axis of rotation. As a result, I will decrease and w will increase. This helps in hitting the ball with greater force.

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The bestest example would be olympic diving. we all have seen almost all the participants tuck their bodies in a way that their legs and arms are closer to their center of rotation while in sir. You must have seen olympic divers ding 3-4 in air rotations before entering water. By tucking in their bodies, they are decreasing the moment of inertia and increasing the angular velocity so as to complete maximum rotations in given time. The moment they have to enter the water, they again open up their bodies to increase the inertia and decrease the angular velocity.