Olivia, 11 Years Old or: "Another season down, another season of random swing mechanics during each at bat"

[OsDad]

That equation doesn't look to be written in a way that would exclude a case for Vbs being 0. That would yield an exit velocity in the direction that the pitch is traveling, right (the negative sign on Vps)? If you held the bat in a vice of some kind, wouldn't a pitched ball hitting the bat still see a change in direction (sign)?

Edit to add: Would the walls of the bat compressing and expanding back out be considered a component of Vbs, to account for the exit velocity being positive?

 

[_MIA_]

That equation doesn't look to be written in a way that would exclude a case for Vbs being 0. That would yield an exit velocity in the direction that the pitch is traveling, right (the negative sign on Vps)? If you held the bat in a vice of some kind, wouldn't a pitched ball hitting the bat still see a change in direction (sign)?

When you actually place a number in for Vps it has to be negative so e.g. for a pitch velocity of 60 (units excluded) you would have, in the Vbs=0 case Vev= -(1/2)*(-60)= 30

Edit: Really I should have labeled all those things as velocities and not speeds since velocities have direction and magnitude (e.g. a vector) while speed is a just a number..but I was lazy.

 

[OsDad]

I assume, outside of this experiment, different bats (with Vbs of 0, in our magical vise) would yield a different actual measured exit velocity. I assume, at that point, finding out exactly what the effect of bat compression is becomes more a matter of materials engineering/physics than strict mathematics?

 

[_MIA_]

I assume, outside of this experiment, different bats (with Vbs of 0, in our magical vise) would yield a different actual measured exit velocity. I assume, at that point, finding out exactly what the effect of bat compression is becomes more a matter of materials engineering/physics than strict mathematics?

Right, the bat properties are taken into account with the coefficient of restitution (which also accounts for ball properties). See below for a portion of an abstract of a paper (referenced at the end) which explains the trampoline effect.

In the high-speed collision between a baseball and bat, most of the initial
center-of-mass kinetic energy is converted into compressional energy in the ball, and
about 75% of that energy is dissipated. Some of the energy is stored in vibrational
modes of the bat, particularly in the so-called “hoop modes”, the most important of
which is a radial deformation with a quadrupole azimuthal dependence. The lowest
such mode has a frequency in the 1-3 kHz range and is strongly excited during the
collision by the local compression of the shell of the bat at the point of impact. Some of
the collision energy that would otherwise have been stored and mostly dissipated in the
ball is stored in this mode. Interestingly and for reasons examined in this paper, much
of this stored energy is returned to the ball, resulting in less overall energy dissipated
and a correspondingly larger ball exit speed. This is popularly called the "trampoline
effect", and the goal of this paper is to examine the physics behind the effect.

http://baseball.physics.illinois.edu/trampoline-v6.pdf

 

[OsDad]

On the subject of Olivia's actual swing. I know FFS isn't around but no one has said anything about TTB. Is that a thing we don't believe in now, since FFS is gone? Is it just something we don't worry about at her age?

 

[clemenslee1]

On the subject of Olivia's actual swing. I know FFS isn't around but no one has said anything about TTB. Is that a thing we don't believe in now, since FFS is gone? Is it just something we don't worry about at her age?

its most certainly still around. And many suggest it for girls your DD's and my DD's age

 

[Work=wins]

On the subject of Olivia's actual swing. I know FFS isn't around but no one has said anything about TTB. Is that a thing we don't believe in now, since FFS is gone? Is it just something we don't worry about at her age?

I won’t comment on TTB at this moment. But I will say the way your dd moves out is creating timing issues and takes away from her sequence. I want the ‘load’ to create the forward move.

But before that can happen. She needs to learn how to create a load. There is no ‘load’ in the swings I viewed.

 

[ANNASDAD]

You guys just made this thread no longer any fun, I’m heading back over to the glove section and see if I can be of any help there!

 

[ANNASDAD]

But before that can happen. She needs to learn how to create a load. There is no ‘load’ in the swings I viewed.

Needs to happen with every kid, but hugely important with a smaller kid!

 

[OsDad]

... I want the ‘load’ to create the forward move.

... But before that can happen. She needs to learn how to create a load. There is no ‘load’ in the swings I viewed.

Do I have to pay extra to find out how you would teach her to load, or how you'd fix her sequence?