# Inelastic Collision Between Two Bodies

• aceking3150
In summary, according to the question, if two masses are in an inelastic collision, their individual momenta will be different, but their combined momentum will be the same.
aceking3150
Homework Statement
It's given through a passage that a leukocyte has a mass of 8x10^-10 and platelet has a mass of 1x10^-11 indicating that they DO have very different masses. But am i wrong by saying that they have a common final momentum since they stick together after colliding? Wouldn't they have both a common final velocity AND a common final momentum since they would have a combined mass of 8.1×10−10. I've missed a few problems like this and I don't get whether I am misunderstanding something or they have them incorrect.
Relevant Equations
m1v1+m2v2 = (m1+m2)v'

If the masses are different the momenta must be different for a common velocity. Unless that velocity is zero.

The question basically asks whether ##m_1v'## equals ##m_2v'##.

I see how the masses are different, but if a perfectly inelastic collision is when the two stick together, wouldn't their masses combine into one? I see how if you look at them with separate masses even after they collide they would have different momenta. But, even though they've stuck together, their masses can be considered separate? I feel like that's what's confusing me.

aceking3150 said:
I see how the masses are different, but if a perfectly inelastic collision is when the two stick together, wouldn't their masses combine into one? I see how if you look at them with separate masses even after they collide they would have different momenta. But, even though they've stuck together, their masses can be considered separate? I feel like that's what's confusing me.

Does that mean that you are not you when you are in a car? Have you and the car merged into a single mass?

If the two cells are considered a common entity after the collision, then it would make no sense to ask about them as separate cells any more. The question would be something like: "what is the momentum of the final object?"

You may not be crazy, but I think you are having an existential crisis.

aceking3150
You appear to be misunderstanding the question. Yes, the two stick together so have the same velocity and can be considered to be a single object with mass m1+ m2 and momentum (m1+ m1)v. But "III" specifically says "the two cells will have a common final momentum" (emphasis mine). It is clearly talking about the two separate cells which have different momenta.

(I can't speak to whether you are crazy or not. But you are wrong. The correct answer is B.)

SammyS, aceking3150 and PeroK
PeroK said:
Does that mean that you are not you when you are in a car? Have you and the car merged into a single mass?

If the two cells are considered a common entity after the collision, then it would make no sense to ask about them as separate cells any more. The question would be something like: "what is the momentum of the final object?"

You may not be crazy, but I think you are having an existential crisis.

Ahhhhh, OK. I see what you mean now. I'm probably thinking of them as combining because my book has given so many examples of them combining entirely.

And as far as an existential crisis, you might be right, haha. Seeing as physics is my weakest area and I'm taking the MCAT in two weeks. :|

PeroK

## 1. What is an inelastic collision?

An inelastic collision is a type of collision where kinetic energy is not conserved. This means that the total energy of the system before and after the collision is not the same. In an inelastic collision, some of the kinetic energy is converted into other forms, such as heat or sound.

## 2. How is momentum conserved in an inelastic collision?

In an inelastic collision, momentum is still conserved. This means that the total momentum of the system before and after the collision is the same. However, because some kinetic energy is converted into other forms, the final velocities of the bodies may be different.

## 3. What factors affect the outcome of an inelastic collision?

The outcome of an inelastic collision is affected by factors such as the masses of the bodies, their initial velocities, and the type of collision (head-on or glancing). The type of material and surface properties of the bodies may also play a role in the outcome of the collision.

## 4. How is an inelastic collision different from an elastic collision?

In an elastic collision, both momentum and kinetic energy are conserved. This means that the total energy of the system before and after the collision is the same, and the bodies involved bounce off each other without any loss of energy. In contrast, an inelastic collision involves a loss of kinetic energy, and the bodies may stick together after the collision.

## 5. What real-life examples demonstrate inelastic collisions?

Some common examples of inelastic collisions include a car crash, a ball hitting the ground, or a hammer striking a nail. In all of these cases, some kinetic energy is converted into other forms, and the final velocities of the objects may be different than their initial velocities.

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