Aerodynamics problem -- Hockey stick hitting another player

In summary: It is possible that the impact happened somewhere other than the skull, but it is more likely that the impact happened on the skull. Even if the impact happened elsewhere, it is still more likely that it happened on the skull than anywhere else.
  • #1
Dillypuff
1
0
Homework Statement
Hello all, this is not really homework but it's a problem I've been trying to solve. Let's say, in a hockey game, a player has a club with a mass of 100g. While running, instead of hitting the disc he hits another player, running in the opposite direction of the motion of the club. With what force does the club hit the other player? Average acceleration of the club is unknown, otherwise I'd simply apply the formula f =m*a. Im grateful for any help!
Relevant Equations
F =m*a
I thought it would make sense to use the formula f=m*a, but I do t know the acceleration and I don't know what is the average acceleration of a hockey club (guess it depends on strength of the player?).
 
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  • #2
Dillypuff said:
Homework Statement:: Hello all, this is not really homework but it's a problem I've been trying to solve. Let's say, in a hockey game, a player has a club with a mass of 100g. While running, instead of hitting the disc he hits another player, running in the opposite direction of the motion of the club. With what force does the club hit the other player? Average acceleration of the club is unknown, otherwise I'd simply apply the formula f =m*a. I am grateful for any help!
Relevant Equations:: F =m*a

I thought it would make sense to use the formula f=m*a, but I do t know the acceleration and I don't know what is the average acceleration of a hockey club (guess it depends on strength of the player?).
There is no way to answer on the given information. During the impact, the force rises from zero to some maximum then declines back to zero. Given the mass of the club and its change in velocity you can find its change in momentum, but without knowing how long the impact lasted, and how the force varied over that time, it is impossible to say anything about the force magnitude.

Aerodynamics??
 
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Likes russ_watters and Delta2
  • #3
haruspex said:
Aerodynamics??
More like Cruel Violent Athletics lol.
 
  • #4
A crude estimate which ignores the fact that the force changes over the duration of the impact is to compute the energy of the impacting club (##E=\frac{1}{2}mv^2##) and equate this to the work done by the club as it dents in the target skull (##W=\vec{F}\cdot \vec{d}##). If you know mass, impact velocity and depth of dent, you can come up with a number for "average" force.

[As @haruspex often points out, the relevant "average" is an average weighted by displacement. Normally when we talk about average force we mean an average weighted by time]
 
  • #5
jbriggs444 said:
##\dots## as it dents in the target skull ##\dots##
No helmet? Must be an MHL game.
Manly Hockey League.
 
  • #6
jbriggs444 said:
A crude estimate which ignores the fact that the force changes over the duration of the impact is to compute the energy of the impacting club (##E=\frac{1}{2}mv^2##) and equate this to the work done by the club as it dents in the target skull (##W=\vec{F}\cdot \vec{d}##). If you know mass, impact velocity and depth of dent, you can come up with a number for "average" force.

[As @haruspex often points out, the relevant "average" is an average weighted by displacement. Normally when we talk about average force we mean an average weighted by time]
Isn't it a bit pessimistic to assume that the point of impact was a skull? Isn't a skate blade or a foot more likely? And perhaps more to the point, isn't it not improbable that unless the other player positioned himself especially for the impact, the collision might stop (or otherwise interfere with the progress of) his foot while the rest of his body hurtled along (roughly) his current velocity vector and then curved downward, thus toppling him? As you and @haruspex seem to me to have ably pointed out: without some additional working assumptions, there isn't enough information in the problem statement to allow a reliable and accurate solution.
 

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