Physics 101

The Renfro

The Renfro

Outsville.com
Silver Member
OK someone help me out here. It's been way too long since college physics so I cheated and used an online calculator for this but it doesn't seem like it could be correct.

A cueball weighs 6oz or .375 lbs
Break speed can vary so I chose 20 24 28 30mph

@20mph = 5.018 lbs of force
@24mph = 7.226 lbs of force
@28mph = 9.835 lbs of force
@30mph = 11.290 lbs of force

They say it only takes 9 lbs of force to break a nose.. According to this the avg pro break of 24mph would allow you to walk away intact....
 
Weight (more specifically, mass) and velocity will give you a calculation of momentum, not force. Force is defined by multiplying mass by acceleration. So you would need to know how fast you are accelerating the ball to determine the force. I'm not sure how useful the info is without a frame of reference.
 
mnsneakypete said:
Weight (more specifically, mass) and velocity will give you a calculation of momentum, not force. Force is defined by multiplying mass by acceleration. So you would need to know how fast you are accelerating the ball to determine the force. I'm not sure how useful the info is without a frame of reference.
Click to expand...

I think you are talking about the force needed to accelerate the ball and not the force applied to the rack by the ball.

You need to calculate the kinetic energy of the cue ball when it hits the rack. This might be the mass times the velocity...... I am not sure if it is the same or not.

Kim
 
I guess the only way to get the proper result would be to know exactly how long the impact lasts and then calculate the acceleration. I would guess that the tip/cueball impact times of .0005 to .001 might be relevant considering billiard ball impacts are considered to be perfectly elastic with a COR of 1.0.......
 
whammo57 said:
I think you are talking about the force needed to accelerate the ball and not the force applied to the rack by the ball.

You need to calculate the kinetic energy of the cue ball when it hits the rack. This might be the mass times the velocity...... I am not sure if it is the same or not.

Kim
Click to expand...


Kinetic Energy= One half of mass times velocity squared.
 
I totally know the answer, just send me a cashiers check for $29.99, I dont like PayPal.. too many strings attached.
 
Systim6 said:
Just go put your face on the spot and let us know how it turns out. lol
Click to expand...

I don't think this would work...the breakspeed app works with sound. With the sound of the cb hitting your face you would never know what the mph of the break was. The sound is completely different. Totally negates the entire experiment :)
 
FYI, I have some calculations and plots of speed, acceleration, and force on the the cue, for different types of strokes, here:

with additional info here:

With typical power shots, the force on the cue usually peaks in the 15-25 pound range.

Enjoy,
Dave

The Renfro said:
OK someone help me out here. It's been way too long since college physics so I cheated and used an online calculator for this but it doesn't seem like it could be correct.

A cueball weighs 6oz or .375 lbs
Break speed can vary so I chose 20 24 28 30mph

@20mph = 5.018 lbs of force
@24mph = 7.226 lbs of force
@28mph = 9.835 lbs of force
@30mph = 11.290 lbs of force

They say it only takes 9 lbs of force to break a nose.. According to this the avg pro break of 24mph would allow you to walk away intact....
Click to expand...
 
The Renfro said:
....
A cueball weighs 6oz or .375 lbs
Break speed can vary so I chose 20 24 28 30mph

@20mph = 5.018 lbs of force
...
Click to expand...
As someone else mentioned, this makes no sense unless you have a time that the force is acting. For example, with just one ounce of force, you could get the cue ball up to 1000 MPH if you pushed on it for about five minutes (unless I slipped a decimal). The problem is that the contact time -- the time that the force is acting on the ball -- is much shorter. For a tip-to-ball contact, it is about 0.001 second (one millisecond). For ball-to-ball contact, it is about 1/5 of that, or 200 microseconds.

During ball-to-ball contact, the force for break-shot speed averages about 1800 pounds with the peak even higher.

Force = mass * deltaV / t
where deltaV is the change in velocity and t is the duration of the collision. This gives the average force and not the peak force which is generally higher. You need to work in a consistent set of units, for which the metric system is a lot easier than dealing with slugs and pound-forces and such.
 
The balls are round. They roll easy. Control the CB with in one square inch and you'll be fine. Johnnyt
 
:cool:------>After reading all this,,I feel so dumb??


:confused:----->"what's this thread about?"

:sorry:--------->"Duh?? I don't know either."

:confused:-------> "It's more better that way,let's go play in the street"


:cool::sorry::confused:--------> "O'tay,,,,,,,,weeeeeee!!!"


LMAO
 
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