Would more force, less force, or the same amount of force be imparted to another object in an elastic collision compared to an inelastic one?

The set up is if I was playing pool and could have a perfectly elastic collision when I hit the cue ball into another ball and then changed the cue ball out for something with the same mass, but would only make perfectly inelastic collisions, which would I want to use to have the most force on the stationary ball?

  • $\begingroup$ Think of two people playing tennis with regular racquets. Now switch then for solid wooden ones. Whats the difference? I use these examples because elastic and inelastic are idealisations. $\endgroup$ – user139561 Dec 19 '16 at 22:15
  • $\begingroup$ @catapillar oohhh. okay, so you are saying that the amount of force applied doesn't matter based on what kind of collision it is? $\endgroup$ – Alexandre Dec 19 '16 at 22:19
  • $\begingroup$ I don't think I can answer homework type questions, sorry. But I don't exactly follow your wording above either. What I can say is look up the definitions of elastic and inelastic, dictionary.com/browse/inelastic-collision and physicsclassroom.com/mmedia/momentum/trece.cfm The ultimate inelastic collision, the pool ball bounces off of the table and into a swimming pool. Hope the links help. $\endgroup$ – user139561 Dec 19 '16 at 22:33

There is no direct relationship between the forces involved and degree of elasticity.

As an example, let's roll two clay balls at each other. The collision is completely inelastic as they stick to each other. If we surround the clay balls with a hard plastic shell, the collision becomes almost completely elastic. The time of interaction is tiny, so the forces felt are very high.

A different possibility is to place a light spring between the two balls. Again the interaction is very elastic, but this time the forces involved are much lower than the clay ball collision.

What you can say is that the impulse (change in momentum) is greater in the elastic collision, and (assuming mass and speed are held constant) determines the speed of the object ball after the impact. High force or low force, the object ball will be moving more quickly after the elastic collision.


The force on the stationary ball doesn't change, regardless of whether its a elastic or inelastic collision.

The only difference is that in an elastic collision (perfect), the kinetic energy of the system remains the same. Meaning the velocity of the two balls (as a total system) doesn't change (I also assume the mass of the balls is constant).

In the inelastic collision, some the kinetic energy is turned into sound, very slight deformation of the ball, etc

So in the second case the total kinetic energy of the system after the collision will be less. BUT the initial force imparted to the ball stays the same, regardless of the collision type.

Hope that helps.


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