# Finding final velocity in a perfectly elastic collision

• ilovedeathcab
In summary, the final velocity of marble B in a perfectly elastic collision with marble A, where marble A has an initial velocity of 1.69 m/s and marble B is initially at rest, is 1.69 m/s. This is determined by the equation v1i+v2i = v1f+v2f, where the initial velocity of marble A and the initial velocity of marble B are equal to the final velocity of marble A and the final velocity of marble B, respectively.
ilovedeathcab
[solved] finding final velocity in a perfectly elastic collision

~~~Two marbles with equal masses collide. Marble A has an initial velocity of 1.69 m/s while marble B is initially at rest. If marble A comes to rest as a result of the initial collision, what is the final velocity of marble B?

* Answers will be accepted if they are within 0.02 of the correct answer.

~Can anyone clarify this?
1. m1v1i + m2v2i = m1v1f + m2v2f

masses cancel...
2. v1i+v2i = v1f+v2f

3. (1.69m/s) + (0m/s) = (0m/s) + v2f

4. 1.69 m/s= v2f

I'm not sure this is correct...

Last edited:
ilovedeathcab said:
~~~Two marbles with equal masses collide. Marble A has an initial velocity of 1.69 m/s while marble B is initially at rest. If marble A comes to rest as a result of the initial collision, what is the final velocity of marble B?

* Answers will be accepted if they are within 0.02 of the correct answer.

~Can anyone clarify this?
1. m1v1i + m2v2i = m1v1f + m2v2f

masses cancel...
2. v1i+v2i = v1f+v2f

3. (1.69m/s) + (0m/s) = (0m/s) + v2f

4. 1.69 m/s= v2f

I'm not sure this is correct...

Looks correct.

thank you so much!

## 1. What is a perfectly elastic collision?

A perfectly elastic collision is a type of collision in which the total kinetic energy of the system is conserved. This means that the objects involved in the collision bounce off of each other without any loss of energy.

## 2. How is final velocity calculated in a perfectly elastic collision?

In a perfectly elastic collision, the final velocity of an object can be calculated using the equation: vf = (m1-m2)v1i / (m1+m2), where vf is the final velocity, m1 and m2 are the masses of the objects involved, and v1i is the initial velocity of the first object.

## 3. How does the mass of the objects affect the final velocity in a perfectly elastic collision?

In a perfectly elastic collision, the final velocity of the objects is directly proportional to their masses. This means that as the mass of an object increases, its final velocity will also increase, assuming all other variables remain constant.

## 4. Can the final velocity in a perfectly elastic collision be greater than the initial velocity?

Yes, it is possible for the final velocity in a perfectly elastic collision to be greater than the initial velocity. This can occur when the mass of the second object is significantly smaller than the first object, causing the first object to rebound with a greater velocity than it had initially.

## 5. Are there any real-life examples of perfectly elastic collisions?

While perfectly elastic collisions are idealized scenarios, there are some real-life examples that closely resemble them. One example is the collision of two billiard balls on a pool table. In this case, the total kinetic energy of the system is conserved and the objects bounce off of each other without any loss of energy.

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