Question for Bob Jewett ...

3andstop

3andstop

Focus
Silver Member
But of course anyone can chime in if they so please.

I'm sure this has been discussed before, but I can't find a definitive thread on it. Regardless, here's the question.

Why is a break shot in 9 ball only about 30mph while Baseball pitches are about 100mph, Hockey slap shots are also about 100mph.

I have to assume, ( maybe this is where I'm wrong) that the CB has to start decelerating once the cue tip leaves contact with the CB. Since there's no motor in the CB I don't think it could continue to accelerate. So the shorter distance to the rack shouldn't be a factor.

Does a pitchers arm move 70mph faster than the forward motion of a cue stick? Does a hockey stick move 70mph faster?

It doesn't seem they would, so, what are the physics behind this ever so slow (relatively speaking) CB? :scratchhead:
 
Much different motion/muscles involved would be my guess. Softball pitches are much closer in muscle usage, and they are closer to 50 MPH based on what I can tell from Google. Factor in the windmill pitch motion that most use, and that probably generates the extra 30 MPH compared to breaking. You've also got much more weight transfer in pitching than breaking. With pitching the whole body is moving forward across a pretty significant distance compared to a break shot where your bridge hand is glued to the table.
 
Our cue stick moves in a Linear direction, therefore we have about 9-10 inches to build up momentem. The Bicep produces most of the speed in the pool stroke. Golf, Softball & Baseball use an ach for more distance traveled. The average pro's average break speed is about 24 mph.
randyg
 
I think it's because the baseball pitch and hockey shot involve a whipping motion that can double or triple the effect of the motion. A lot of energy is stored in the whipping motion and released at the apex of the motion.

A pool cue is a pretty solid object that doesn't have much whipping energy.
 
A pitch or slap shot can also be off an inch without the ball/puck flying off of the playing surface and out of bounds. A pitch is thrown directly from the hand, so there's no real problem with proper contact in that manner. A puck is smacked by a much larger surface, also reducing the chance for mis-sticking, as well as the fact that the puck lies, more or less, flush with the ice, guaranteeing an easier hit. And, as others mentioned, both of those involve an orbital movement, which increases the speed of the outlying object, whereas in pool the motion is mainly in a straight line from around the hip.

I'm sure that you can make a cue ball travel faster than 30 mph, but I doubt it's going to be safe for anybody standing nearby. You could also risk damaging the equipment(felt, cue, etc) by trying to put all of your power into it. Try the Happy Gilmore on it and let us know the results. :thumbup:

Here's another example for the orbital motion.. a wind turbine's hub does not spin very fast, but the blade tips can reach speeds of 120mph to be table to cover the distance needed for the same rotation.
 
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hockey

A cue tip is just 13 millimeters in diameter, while a cue ball is 2 1/4 inches in diameter, which is about 57 millimeters. A cue tip is much softer than a cue ball, which is over four times as big. Hit something big and solid with something small and soft and you can only generate so much power.

By comparison, the part of the hockey stick used to strike the puck is much bigger than the puck and just as hard.

Another major difference is that one can put much more of their weight behind a hockey slapshot than on a nineball break, in part because they can generate high velocity with body movement in the direction of the shot and a much bigger backswing than is possible in pool.
 
My son hits a slap shot at least 70.
His whole body leans in toward the shot, stick held very high, all the while skating toward the target at who know how fast. Suddenly the puck is right there, the hips and torso begin to turn bringin down his arms and hands. The stick hits the ice maybe an inch before the puck causing the stick to bend like there is no tmrw. The hockey stick recovers as his energy continues to produce a tremendous blow to hockey puck.Pros hit it well over 100. my boy just told me world record is 109 but I think it is lots more than that.
Same thing with baseball, A complete total body movement starting with the toes and ending at the fingertips.
I remember reading a book by Robert Byrne where they took of the end rail off to accuratly measure break speed. the max came in at about 30 something mph. Robert credits the persons ability to hit it that fast to a lifitime of martial arts.
steven.
[seeya]
 
The length of the acceleration is vastly different, and then there are some changes in the geometry of that acceleration.

When a baseball pitcher throws a baseball, there is a circular arc of at least 7 feet in length where the arm is adding velocity to the BB. In addition the pitchers body moves forward some 2 feet while the arm is inmotion. The combination delivers a lot of energy (i.e. speed) into the BB.

When a player strokes a CB the arm supplying the motion has 12-18 inches of forward motion before making contact with the CB, and any body movement must be seriously constrained or the hit may not go where intended.
 
MitchAlsup said:
The length of the acceleration is vastly different, and then there are some changes in the geometry of that acceleration.

When a baseball pitcher throws a baseball, there is a circular arc of at least 7 feet in length where the arm is adding velocity to the BB. In addition the pitchers body moves forward some 2 feet while the arm is inmotion. The combination delivers a lot of energy (i.e. speed) into the BB.

When a player strokes a CB the arm supplying the motion has 12-18 inches of forward motion before making contact with the CB, and any body movement must be seriously constrained or the hit may not go where intended.
Click to expand...


:thumbup:

Simply put, the end of a bat or a club moves a lot faster than a cue because you swing a bat or a club in a wide arc. The end of the club or bat is moving much faster than the handle...the handle is moving at around the speed that your cue would.

You want faster break speeds? Stry swinging the cue like a bat. :D


.
 
Chopdoc said:
:thumbup:

Simply put, the end of a bat or a club moves a lot faster than a cue because you swing a bat or a club in a wide arc. The end of the club or bat is moving much faster than the handle...the handle is moving at around the speed that your cue would.

You want faster break speeds? Stry swinging the cue like a bat. :D
.
Click to expand...
Creating a bigger arc is how power breakers get more speed. They stand up as they swing the cue so they can use their whole arm pivoting at the shoulder rather than just the forearm pivoting at the elbow.

pj
chgo
 
3andstop said:
But of course anyone can chime in if they so please.

I'm sure this has been discussed before, but I can't find a definitive thread on it. Regardless, here's the question.

Why is a break shot in 9 ball only about 30mph while Baseball pitches are about 100mph, Hockey slap shots are also about 100mph.

I have to assume, ( maybe this is where I'm wrong) that the CB has to start decelerating once the cue tip leaves contact with the CB. Since there's no motor in the CB I don't think it could continue to accelerate. So the shorter distance to the rack shouldn't be a factor.

Does a pitchers arm move 70mph faster than the forward motion of a cue stick? Does a hockey stick move 70mph faster?

It doesn't seem they would, so, what are the physics behind this ever so slow (relatively speaking) CB? :scratchhead:
Click to expand...

We don't actually know what the speed is because it travels such a short distance. I would say when the cueball hits the rack, it is still accelerating.
 
macguy said:
We don't actually know what the speed is because it travels such a short distance.
Click to expand...
Break speed is measured very accurately by a simple phone app.

I would say when the cueball hits the rack, it is still accelerating.
Click to expand...
Acceleration takes force. The force on the CB ends when the ball leaves the cue tip, when the ball immediately begins decelerating because of friction with the cloth and air.

pj
chgo
 
Patrick Johnson said:
Break speed is measured very accurately by a simple phone app.


Acceleration takes force. The force on the CB ends when the ball leaves the cue tip, when the ball immediately begins decelerating because of friction with the cloth and air.

pj
chgo
Click to expand...

You may be right. Does the phone app work by sound? Have you checked the break speed at different distances? In other words move the cueball a foot closer to the rack and see if you get a faster speed.
 
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macguy said:
You may be right. Does the phone app work by sound? Have you checked the break speed at different distances? In other words move the cueball a foot closer to the rack and see if you get a faster speed.
Click to expand...

i believe it can only work by sound :) and it tells you where you should place it on the table. i have used my iphone together with an android and they always measured virtually identical speeds.
 
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I think the term used is "blocking" but I did a search and found nothing. I learned about it awhile back. Basically the object used to propel an object ( arm,hockey stick, etc, flex perpendicular to intended path of movement. Think of a fishing rod, if it did not flex you could only throw a lure however fast you can swing your arms. But since it does you can now add the energy stored in the flex of the shaft on top of the speed you swing your arms. In throwing a baseball they break it down like this I think it was three blocks. Block 1 the speed which you can twist your body, Block 2 the speed which you can rotate your arm at your shoulder and Block 3 the speed at which you can snap your wrist.

Block 1 = 20 MPH
Block 2 = 30 MPh
Block 3 = 30 MPH

If you tried throwing a baseball with out using your wrist and holding your arm straight out only twisting your torso or upper body you would only achieve 20 MPH. But the energy builds on itself in the complex movement of throwing allowing us to achieve better results.
Applying this to the break in pool doesn't work since its only one block (the bicep or arm swing however you look at it).
 
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macguy said:
You may be right. Does the phone app work by sound? Have you checked the break speed at different distances? In other words move the cueball a foot closer to the rack and see if you get a faster speed.
Click to expand...

It works by measuring the time interval between the cue hitting the cue ball and the cue ball hitting the rack, not volume. On the app you can change the starting position of the cue ball, the speed is the same if you place the cue ball accurately enough.

PJ is right. Due to conservation of momentum, the cue ball stops accelerating after impact of the cue because there is nothing pushing it forward. The friction of the cloth and air resistance decelerate the cue ball, but probably only very slightly.

The main difference between a pitch in baseball and a break shot is leverage. You can put the same amount of power into both activities, but the pitch will be faster because you are using your whole arm as opposed to mainly the forearm. Some pool players try to incorporate the upper arm, but it is nearly impossible to incorporate the whole length of the arm due to the table and your body getting in the way.

Some other factors in the difference in speed are that a throw is also generally easier to coordinate with the rest of your body resulting in better timing and it is much easier to incorporate a whipping action of the wrist with the hand facing forward rather than sideways as in pool.
 
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macguy said:
Does the phone app work by sound?
Click to expand...
Yes, by measuring the time between the sound of the stick hitting the CB and the CB hitting the rack (you tell it where you're breaking from).

Have you checked the break speed at different distances? In other words move the cueball a foot closer to the rack and see if you get a faster speed.
Click to expand...
Yes, you can move the CB's starting position a fraction of an inch and the program easily takes it into account.

pj
chgo
 
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Patrick Johnson said:
Creating a bigger arc is how power breakers get more speed. They stand up as they swing the cue so they can use their whole arm pivoting at the shoulder rather than just the forearm pivoting at the elbow.

pj
chgo
Click to expand...

DING! DING! DING! This. This is also why power breakers use a longer bridge, too. In a recent commentary, Earl Strickland had mentioned he was trying a longer bridge when breaking and it seemed to work "for some reason". This is the reason.

Another example, picture hitting a golf ball. Now picture only swinging back 8-12 inches in your swing. Appreciate the difference?
 
Yeah, basically there's little to no mechanical advantage involved.

Minimum length of lever, very little stored kinetic energy, loading (physical or mechanical) or momentum.

All of these things exist in pretty high degrees in the other sports referenced for comparison.

And no" the CB certainly does not accelerate after it leaves the cue tip. ;)
 
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