Relative velocity and force relationship

  • #1
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This is something related to my job.

There are two components A & B both travelling the same direction but at a different velocity. I can find out the exact velocity of both the components when they just hit each other, thus relative velocity is known.

Is there a way I find out the force exerted during this collision? I know the mass properties (mass & inertia) of A & B.

Pl. help

P.s. - I am aware that force is a function of acceleration (and hence time). However, I am clueless here as what time to be considered.
 

Answers and Replies

  • #2
425
77
This is something related to my job.

There are two components A & B both travelling the same direction but at a different velocity. I can find out the exact velocity of both the components when they just hit each other, thus relative velocity is known.

Is there a way I find out the force exerted during this collision? I know the mass properties (mass & inertia) of A & B.

Pl. help

P.s. - I am aware that force is a function of acceleration (and hence time). However, I am clueless here as what time to be considered.
If you knew something about the time, you could work out the impulse from the change in momentum and then work out the force from the time over which the collision took place.
 
  • #3
CWatters
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You can't solve it without more information. Clearly two water balloons would be in contact with each other for longer than two blocks of steel during similar velocity collisions.
 
  • #4
CWatters
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Can you put accelerometers on your components?
 
  • #5
sophiecentaur
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This is the sort of question that's often asked in the context of car crashes and personal injuries (punches etc.) and the 'force' of the collision is what people want to know. And it's really hard!!! To find it, you need to know the details of the structure of the two components because they will deform whilst the momentum is re-arranged between them. It may be that you don't actually need to know those details - unless you are worried about damage - and you can assume a perfectly elastic or totally inelastic collision and that can give you some bounds for the resulting motion.
 
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  • #6
sophiecentaur
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@k.udhay If you are able to do some experimenting, you could find the 'spring constant' of the components and treat them as colliding springs. With a bit of ingenuity, you could work out the Potential Energy in the springs during contact and that could tell you the sort of forces acting. Whether it would be worth going into all that would depend on your facilities and technical know how.
 
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  • #7
CWatters
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Some objects clearly cannot be compressed more than a certain amount during a collision or damage will occur. You can probably use that to set a lower bound on the forces involved.
 

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