## Thursday, March 18, 2021

### Who Really Supplies The Power: The Pitcher or The Hitter?

I always grew up hearing this from coaches when a power pitcher was on the mound:

"He'll supply the power. Just make contact."

It seemed to make sense. The faster the ball hits the bat the further it will travel after impact.  Except the science says otherwise.

The formula to determine the speed at which the ball rebounds off the bat is:

vexit = q vpitch + (1 + q) vbat

EXIT VELOCITY (OFF BAT) = ea * PITCH VELOCITY +

(1 + ea) * SWING SPEED

Where vexit  is the ball exit velocity, vpitch is the velocity of the pitched ball and is the vbat  speed of the bat.  "q" is COLLISION EFFICIENCY

Collision efficiencyvalue is between 1.0 and 2.0 depending on the squareness  of the hit. A well hit ball with a wood bat on the sweetspot gives a value of 2.0.   A detailed explanation of COLLISION EFFICIENCY is in this paper.  I used a value of 1.5 for q with graphs below.

So what does this formula tell us?  It shows mathematically that the batter's swing speed is 6 times more important than the pitch speed in creating higher exit velocity!

Graphs below show the exit velocities for 5 several bat speeds (60, 65,70,75,80 mph) as pitch speed increases from 65 to 100 mph.

Notice how flat the exit velocity increases are for each bat speed. While there is an increase as the pitch speeds increase (pitch speed does have an influence) it's not a large one.

When we increase both the pitch speed AND the bat speed, the exit velocity increases more sharply.

So for a pitch speed of 65 mph and a relatively show bat speed of 60 mph, the exit velocity after a decently hit ball would be around 79 mph. An increase the pitch speed to 85-90 mph with a commensurate increase in bat speed to 70-75 mph would yield an exit velocity above 95 mph. Similarly a bat swung at 80 mph making contact with a 95 mph pitch would cause the ball to leave the bat at 105+ mph.

Bat speed not pitch speed supplies most of the power!

## Thursday, March 04, 2021

### What Locations See The Greatest Day-to-Day High Temperature Changes?

We often think that our location has the greatest weather changes. Often times that's true. I can count the numbers of times when people say "That's Ohio weather. Wait 5 minutes and it'll change." The perceptions are powerful. I wrote about this a few years back which you can read HERE. But when we look at the entire middle of the country, the locations that see the greatest frequency of day-to-day temperature change might surprise you.

How did I figure this out? I downloaded the high temperatures for each day for 20 cities over the last 50 years. (I would have downloaded further back in time and more cities but I ran out of time and computer speed). I found the day-to-day temperature differences and counted up the instances when it was more than 20 degrees. Finally I tabulated the totals for each month and graphed them below.

The central of the US features the largest day-to-day temperature swings especially in March and April. Eastern Nebraska, northeastern Kansas, northwestern Missouri and portions of Iowa and southern South Dakota.

Also notice the pockets of higher frequency across Ohio and western Pennsylvania in March. Another localized pocket is located over northern Illinois and portions of Wisconsin in May and June.

When you look at the biggest changes between daily high temperature and low temperatures, the high frequency area shifts to the panhandle of Texas and Oklahoma.

 Image Courtesy: NWS Amarillo (Chris Kimble)

What is the largest temperature difference between high temperatures and low temperatures between days in Cleveland?  Lows were close to ZERO the morning of March 8, 1986. By the afternoon of March 9th, the temperature was in the lower 60s...almost 70 degrees by the 10th!