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Yratelev

golf ball v egg

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Yratelev    130
Hi, Imagine a golf ball and an egg fired directly towards each other at say 500mps. They are of equal mass, and both intact just before the collision. Now, I think its pretty certain the egg will smash into tiny pieces while the ball is unscathed, but what will the speed of the golf ball be and in which direction after the collision (assume no gravity)? Will the golf ball just go through the egg taking relatively little speed loss, or, because they are equal mass, will the golf ball slow down to almost stationary because the momentum of the egg has slowed it down regardless of the fact the egg got smashed? Thanks, Yratelev

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Guest Anonymous Poster   
Guest Anonymous Poster
That depends on so many variables that it almost makes the question meaningless.

Are the objects spinning? At what orientations are they when they collide (An egg being ovoid is stronger at some points than others)? What sort of egg is it (size, mass, shell thickness, sheer strength of shell, is it hard boiled, what shape is it) What is the mass of the golf ball? How is it constructed? What material is it? Is it an old fashioned leather golf ball? Do they hit each other perfectly central?

All you can really say is that if the egg does break (which is not certain), then the golf ball will be slowed by some factor and would most probably also be defelected in some way.

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Yratelev    130
Quote:
Original post by Anonymous Poster
That depends on so many variables that it almost makes the question meaningless.

Are the objects spinning? At what orientations are they when they collide (An egg being ovoid is stronger at some points than others)? What sort of egg is it (size, mass, shell thickness, sheer strength of shell, is it hard boiled, what shape is it) What is the mass of the golf ball? How is it constructed? What material is it? Is it an old fashioned leather golf ball? Do they hit each other perfectly central?

All you can really say is that if the egg does break (which is not certain), then the golf ball will be slowed by some factor and would most probably also be defelected in some way.


I really cant believe someone posted that. Dude, its an egg and a golf ball, two everyday objects that I put in to make the problem seem easier to digest. Make whatever assumptions you feel nessacary.

Yratelev

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Guest Anonymous Poster   
Guest Anonymous Poster
It all depends on the mass ratios of the two objects, the hardness of the bodies, and the size. Seems the masses are closed to each other the egg has sufficient momentum to deflect the ball even thought lot of it be dispersed on the component of the egg flying apart. However a good part of these components will still be hitting the ball in direct collision.

This question is similar to what cases more damages a solid asteroid hitting a planet or one that was pulverized but an explosion, they both cause the same damage.

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joanusdmentia    1060
Quote:
Original post by Yratelev
Now, I think its pretty certain the egg will smash into tiny pieces while the ball is unscathed


If the egg's longest axis was in the direction of travel and it was spinning, I don't think I'd want to place any bets on that one.

Of course, that's a *big* if :)

EDIT: Oh, and in answer to your question, it would go left.

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ghosted    445
Irrespective of what happens to the egg you'll likely have to drop a shot and play from the spot it landed in making any chance of hitting the green on your next shot unlikely.

No seriously, when the two collide the force acting upon the egg from the golf ball will be larger than that acting the other way. The exchange of energies will see some spent in blowing the egg apart and some on noise, the remainder will simply slow the gold ball down slightly.


Think of it like this: when my go kart, rolling on a flat surface, hits my friend I experience a thump and I'm thrown forward in the seat slightly but continue onwards with a worried look on my face. However as I continue on I'm struck by a bus coming the other way. It makes a mess of my worried looking face and I end up carried backwards by the bus. The bus will have suffered a slight drop in speed but it will have been tiny as the energy exchange is dependent upon the mass of the objects involved (and the rigidity in the case of the egg).

Hope that helps.

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Squirm    481
Oh, come now, surely we can actually answer at some point?

Both parts have energy and momentum. Momentum will be conserved. Energy will be lost. Unfortunately some momentum will be retained by remnants of the egg, but we have limits - we know the golf ball will change momentum and energy by at least 0 and at most the momentum/energy of the egg.

I would say forget elasticity, give the egg a 'splat' coefficient, between 0.0 and 1.0, assume a totally inelastic collision, and then multiply the resulting change in velocity of the golf ball by the splat coefficient. An egg with a high splat value will immediately splat and have no effect. An egg with a very low splat coefficient will only just break and deflect the golf ball quite significantly.

This branch of phsyics (aka the splat approximation) is atleast as valid as the rigid body mechanics approximation in this case. The only thing you might try is multiplying the change in energy by the splat, instead of the change in momentum (v^2 instead of v).

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Sneftel    1788
Well, hm.

An introductory college physics textbook would try to shoehorn this as a "perfectly inelastic collision". Two bodies flying through space hit and stick to each other. Momentum is conserved, so the final velocity vector is v = (v1*m1 + v2*m2)/(m1+m2). For equal masses and opposite velocities, that means zero.

In this case, however, the situation may be different. If the golf ball hits the egg on a side, it's likely that the shock wave produced in the egg would act to split the egg in half, the pieces flying around the egg but not (for the most part) adhering. In this case, there would be significant speed loss, but both the golf ball and the egg would still be flying quite fast. The exact numbers, of course, depend on quite a lot of variables.

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kodeninja    214
I tend to agree with the fact they would both stop, but the fact that the egg is more brittle then the golf ball, it would make sense that the conveserved momentium in the egg would not all be directed into the golf ball and instead be divided amoung the pieces of the egg (perhaps not equally) but this would mean that the egg loses its momentimum faster then the golf ball and the golf ball continues on, but at a much less speed...

At first this question reminded me of the age old question...
Which is heavier? A pound of feathers or a pound of lead? :P

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Guest Anonymous Poster   
Guest Anonymous Poster
Quote:
Original post by ghosted
No seriously, when the two collide the force acting upon the egg from the golf ball will be larger than that acting the other way.


Not true. If they are both of equal mass (as stated by the original poster) then the impulse force on impact will be the same for both objects. It's just the objects' reaction to those forces that would be different.

I imagine most of the force applied to the egg would result in breaking it and imparting a radial 'outwards' force from the lateral line of the collision.

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Dmytry    1151
Well, let's assume that them have equal mass, that we use egg of some bird that have round eggs (yay), or at least axis of egg points in direction of motion, that them are not spinning, that we do it in weightless conditions, etc. Let's assume egg breaks into pieces.

So, we have that:

before:
egg golf ball
[grin]---> <---[smile]
(both are moving towards eachother with equal speed and have equal mass)
after:
,^'
%`~.
<--[smile] *center of mass of egg-->
.",
~,.

with ball on the left and pieces of egg on the right.
(note: it might actually bounce at sufficiently big speed. We need to make experiment)


Note that due to conservation of momentum, center of mass of system is stationary before and after collision.
That is, sum of M*V of every flying piece is 0. (for all directions)
This means that center of mass of egg flies in opposite direction to center of mass of golf ball, with equal speed.(or that both is stationary).
So, center of mass of golf ball "loses" speed as much as as center of mass of egg does. (It is worth mentioning that center of mass of egg could be stationary while parts of egg are flying in opposite directions with big speed)
I think I answered OP's question.

For more specific results(to compute velocity of motion, etc), one need empirical data (i.e. make experiment)

edit: cound not resist to picture egg as "[grin]" and golf ball as "[smile]"

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Max_Payne    757
500 mps? I assume you mean miles per second? Bleh, you americans need to learn to use real scientific units. But anyways...

If both objects were travelling at 500 miles per second, the golf ball would most likely *not* remain intact. Just to give you an idea, the space shuttle travels at approximately 8 KM/s when entering orbit... And 500 miles per second is a few hundred times that velocity. An egg might appear quite weak, but at such speed, it would actually have quite alot of kinetic energy (enough to kill anyone that would get hit by it). So just hitting tiny particles of the egg's shell, and the liquid contained in it would squash the golf ball, which would be scattered into multiple fragments.

Assuming the egg has a mass of 0.1kg, that means it has over 32.3 kilojoules of kinetic energy.

Most likely, if you could do this in space, both the egg and the golf ball would be scattered into fragments, which would continue their course in opposed directions. I believe most of the fragments that leave the collision site at greater speed would leave in random trajectories that form a parabolic shape. There would also be slower fragments whose speed has been greatly reduced, and perhaps a few fragments that are almost still at the collision site.

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Fingers_    410
You must simulate the egg as a collection of small particles, with appropriate forces holding them together until broken by the impact. You could ask the guys who simulated the planetesimal collision that created the moon :)

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Max_Payne    757
I just did some calculations, and it would seem that the kinetic energy of the egg (assuming a mass of 0.1kg) is the equivalent of 7kgs of TNT. I still say the golf ball is dead ;)

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Dmytry    1151
I think he mean 500 meters per second (not miles per second).

*********************************************************************************
Indeed with 500 miles per second both ball and egg will evaporate, heck, them will turn into ionised plasma!
One gramm will carry energy
click to see computation (Max, you forgot to square velocity and greatly underestimated the power)
> 300 MJ
For some idea, TNT have energy of 15 5 MJ per KG.
edit: scrap that. Accordinly to
this site , one kg of TNT have energy of bit less than 5MJ. We can assume it's 5.

So explosion will be 20 000 60 000 times more powerful than TNT (1 gram of egg equivalent to 20kg 60kg of TNT), so there will be temperatures around million degrees (I think).

There will be some _strong_ flash, and intense light will evaporate all pieces that would escape direct collision.[grin] Maybe (big maybe) you'll even get some nuclear reactions if egg contains deiterium[grin].

*************************************************
At 500 meters per second, effects will not be so dramatic, but probably golf ball will be damaged somewhat. (maybe even broken into pieces)

[Edited by - Dmytry on July 19, 2005 1:03:50 PM]

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Guest Anonymous Poster   
Guest Anonymous Poster
Considering the speed of sound is about 340 m/s, we are taking almost match 2, I say at 550 m/2 both the ball and the eggs are pulverized on the impact

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Max_Payne    757
Quote:
Original post by Dmytry
I think he mean 500 meters per second (not miles per second).

*********************************************************************************
Indeed with 500 miles per second both ball and egg will evaporate, heck, them will turn into ionised plasma!
One gramm will carry energy
click to see computation (Max, you forgot to square velocity and greatly underestimated the power)
> 300 MJ
For some idea, TNT have energy of 15 MJ per KG.
So explosion will be 20 000 times more powerful than TNT (1 gram of egg equivalent to 20KG of TNT), so there will be temperatures well above 100 000 degrees (I think).

There will be some _strong_ flash, and intense light will evaporate all pieces that would escape direct collision.[grin] Maybe (big maybe) you'll even get some nuclear reactions[grin].

At 500 meters per second, there will not be such dramatic effects, but probably golf ball will be damaged somewhat.


The symbol for meters per second is m/s, not mps.

That said, I did make a mistake in the calculation, but its not about squaring the velocity...

The velocity is 500 miles per second, which is approximately 804500 m/s.

This means that the kinetic energy of the egg, for a mass of 0.1kg is over 32 Gigajoules.

1 metric ton of TNT releases 4.184 megajoules of explosive power. Hence the egg has a kinetic energy equivalent to over 7.6 kilotons of TNT (a small nuclear bomb).

Those calculations should be more correct for a velocity of 500 miles per second.

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Dmytry    1151
Quote:
Original post by Max_Payne
Quote:
Original post by Dmytry
I think he mean 500 meters per second (not miles per second).

*********************************************************************************
Indeed with 500 miles per second both ball and egg will evaporate, heck, them will turn into ionised plasma!
One gramm will carry energy
click to see computation (Max, you forgot to square velocity and greatly underestimated the power)
> 300 MJ
For some idea, TNT have energy of 15 MJ per KG.
So explosion will be 20 000 times more powerful than TNT (1 gram of egg equivalent to 20KG of TNT), so there will be temperatures well above 100 000 degrees (I think).

There will be some _strong_ flash, and intense light will evaporate all pieces that would escape direct collision.[grin] Maybe (big maybe) you'll even get some nuclear reactions[grin].

At 500 meters per second, there will not be such dramatic effects, but probably golf ball will be damaged somewhat.


The symbol for meters per second is m/s, not mps.

That said, I did make a mistake in the calculation, but its not about squaring the velocity...

The velocity is 500 miles per second, which is approximately 804500 m/s.

This means that the kinetic energy of the egg, for a mass of 0.1kg is over 32 Gigajoules.

1 metric ton of TNT releases 4.184 megajoules of explosive power. Hence the egg has a kinetic energy equivalent to over 7.6 kilotons of TNT (a small nuclear bomb).

Those calculations should be more correct for a velocity of 500 miles per second.

1 metric ton of TNT releases 4.184 giga joules.

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Guest Anonymous Poster   
Guest Anonymous Poster
At 500 miles/seconds we are taking about relativistic effecs now, the both the mass of the ball and the egg get magnified by some factor.
Hey if we keep speculating soon this egg will be powerful enough to destroy earth,Hey I have and idead, let us just crack the egg, make and omelet and eat it before is too late.

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Max_Payne    757
Quote:
Original post by Anonymous Poster
At 500 miles/seconds we are taking about relativistic effecs now, the both the mass of the ball and the egg get magnified by some factor.
Hey if we keep speculating soon this egg will be powerful enough to destroy earth,Hey I have and idead, let us just crack the egg, make and omelet and eat it before is too late.


There are no significant relativistic effects at 804.5 Km/s. Thats only 0.00268c (0.268% of the speed of light).

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