Possible to calculate speed with these numbers?

[QwertySham]

So I don't have a radar gun to find out how fast I'm throwing and it's been a couple years since I was last under the gun.

I suck at math to say the least so I'm not even sure if it's possible to find the speed of the baseball but here's the numbers.

The ball traveled 29 feet.
My camera records in 30 frames per second and took 9 frames to hit the net.

So I'm assuming you could find the amount of time that it took the ball to go from my hand to the net and then take that amount of time and figure out how many feet per second that is, then figure out the speed in MPH after that?

From that information is it possible to figure out the speed in MPH?

I hate math

[Masark]

9 frames at 30fps = 0.3 seconds

29 feet in 0.3 seconds = 96.6~ feet per second = 65.91 miles per hour

[D4n13le]

Should be an average speed of ~65.90 mph.

[Arlon]

I can understand hating math... But this...

[chrisberb]

Math isn't my strongest but i'll take a shot at it
Hmm..29 feet, 9 frames..carry the 1..move the decimal place..divide by 3
I come up with about $37?

[QwertySham]

9 frames at 30fps = 0.3 seconds

29 feet in 0.3 seconds = 96.6~ feet per second = 65.91 miles per hour

Well shit, losing 50 lbs of fat slowed me down ~12 mph. Huh. Well that's sad. haha well thank you Masark

Edit: and others!

[Darnash]

Yup, 65.91 mph. 1/187.07 miles per 0.3 seconds (which you can get by dividing 29 feet into the 5280 feet in a mile, and by dividing 9 by the 30 frames/second respectively) is .0183 miles/second (divide both by 0.3), which is 1.098 miles/min (multiply by 60 seconds/min), which is 65.91 mph (multiply by 60 min/hour).

[QwertySham]

I can understand hating math... But this...

Let's just say I didn't care to pay attention in math during High School or much of Middle School for that matter. Didn't/don't plan on pursuing a career that involves math so I regretfully didn't pay much attention.

- - - Updated - - -

~66 is sad. I threw faster my freshman year of HS and I'm now in my 2nd year of college. Maybe I picked a lazy pitch to pick as my test. Time for round 2...

[Julian Rayne]

9 frames to hit the net means between 8 and nine intervals. Each interval is 1/30 of a second. Estimating 8.5 intervals, time taken is 8.5/30 = 0.283 s.
Speed = distance / time = 29*30/8.5 = 102.35 feet/s

1 mile = 5280 feet and one hour = 3600 seconds.
So mph = fps * 3600/5280 = 102.5*3600/5280 = approximately 69.77 mph.

[TEHPALLYTANK]

Let's just say I didn't care to pay attention in math during High School or much of Middle School for that matter. Didn't/don't plan on pursuing a career that involves math so I regretfully didn't pay much attention.

- - - Updated - - -

~66 is sad. I threw faster my freshman year of HS and I'm now in my 2nd year of college. Maybe I picked a lazy pitch to pick as my test. Time for round 2...

Perhaps brush up on basic math first so you can figure out how much you're improving.

[Twoddle]

If it took 9 frames from start to finish then the total time is 8/30s from the first frame to the last.

29 feet in 8/30s = 29 * 30/8 = 108.75 feet/s

108.75 feet/s = 108.75 * 0.682 mph

= 74.15 mph

[Arlon]

Let's just say I didn't care to pay attention in math during High School or much of Middle School for that matter. Didn't/don't plan on pursuing a career that involves math so I regretfully didn't pay much attention.

Well, it´s your choice really and it´s great if you wont ever need this. It´s just suprising since this is entry-level kinematics calculation.

[QwertySham]

Perhaps brush up on basic math first so you can figure out how much you're improving.

Respect the advice. I guess if there's any one thing I'm willing to remember from math it's how to solve these problems. Call me an idiot but everyone here has different answers and I tried plugging my new numbers into some equations presented here, and I'm lost still.

Mostly everyone came up with ~65.9 But I also see a 74, a 69, and somehow I make money by throwing a baseball with an answer of $37.

So I went out a threw a couple more. We're looking at 7.5 frames at 28 feet from hand to net. Shorter distance because I actually measured the distance from my release point (seen from the camera) to the net. Estimated previously because from the rubber to the net it's 34 feet; give or take an inch.

Also, could I get an equation for this? If everyone is using the same numbers how are people getting different answers?

[Spectral]

I'm really discinlined to trust a camera for this sort of work.

[Monolith of Mazes]

dont the frames have timestamps?

[Julian Rayne]

Also, could I get an equation for this? If everyone is using the same numbers how are people getting different answers?

Because the camera frames introduces an element of ambiguity into the data. 9 frames could mean either 8 or 9 intervals. There's an uncertainty of 12.5% right there. Which exactly accounts for the answers ranging from 65.9 to 74.1. If you post the first and last frames you could get a more accurate answer.

Equation: Speed in MPH = (distance * 3600 * camera frame rate) / (5280 * number of camera intervals)

[admeteora]

first frame (ball left arm): time A?
last frame (ball reached net): time B?
distance D between net and arm: 29
(D / (time B - time A)) x 0.681818 = speed in mph
Something like that could work too you know

or even simpler (distance (feet) / travel time (second)) x 0.681818 = speed in mph

frames are just as much of an approximation as time since your camera isnt very precise.

[QwertySham]

I'm really discinlined to trust a camera for this sort of work.

It's really not ideal, especially at 30fps. Going frame by frame you can't actually see the point at which the ball leaves my hand because you just see a blur. Also, the sound of the ball hitting the net isn't going to be exact either, but close enough. Need a slow-mo cam, but at those prices I might as well just buy a radar gun. lol

[belfpala]

I'm really discinlined to trust a camera for this sort of work.

Why? Just put a +/- of 1 frame (and apply it to the resulting velocity calculation).