# Calculating Velocity After Elastic Collision: Kinetic Energy Problem

• ashvinthecha
In summary, the conversation discusses a head on collision between two balls, one with a mass of 0.8kg and initial velocity of 8.0m/s and the other at rest with a mass of 0.4kg. The question asks for the velocities of each ball after the perfectly elastic collision. The solution involves using equations for energy and momentum conservation to solve for the final speeds.
ashvinthecha

## Homework Statement

A ball of mass 0.8kg moving initially at 8.0m/s has a head on collision with a 0.4kg ball that is at rest. If the collision is perfectly elastic, what is the velocity of each ball after the collision?

Ek=(mv2)/2

## The Attempt at a Solution

I found the kinetic energy of the first ball, then split the knietic energy between the two balls after the collision to individually find the velocity of each.

ashvinthecha said:
I found the kinetic energy of the first ball, then split the knietic energy between the two balls after the collision to individually find the velocity of each.
What do you mean by 'split the kinetic energy'?

Hint: What else is conserved during the collision besides energy?

Doc Al said:
What do you mean by 'split the kinetic energy'?

Hint: What else is conserved during the collision besides energy?

I divided the total kinetic energy by two... and is momentum the answer to your question

ashvinthecha said:
I divided the total kinetic energy by two...
You cannot assume that the kinetic energy divides equally.
Yes. Use conservation of momentum and energy to solve for the final speeds.

Doc Al said:
You cannot assume that the kinetic energy divides equally.

Yes. Use conservation of momentum and energy to solve for the final speeds.

How do I do that?

ashvinthecha said:
How do I do that?
Write equations for energy conservation and momentum conservation, then solve them.

## What is kinetic energy?

Kinetic energy is the energy an object possesses due to its motion. It is a scalar quantity that depends on both the mass and velocity of the object.

## How is kinetic energy calculated?

Kinetic energy is calculated using the formula KE = 1/2 * m * v^2, where m is the mass of the object and v is its velocity. The unit for kinetic energy is joules (J).

## Is kinetic energy conserved?

According to the law of conservation of energy, energy cannot be created or destroyed, but it can be converted from one form to another. In the case of kinetic energy, it can be converted into other forms of energy, such as potential energy, but the total amount of energy remains constant.

## How does kinetic energy affect an object's motion?

Kinetic energy is directly proportional to an object's mass and the square of its velocity. This means that the greater an object's mass and velocity, the more kinetic energy it possesses. In terms of motion, the higher an object's kinetic energy, the faster it will be moving.

## What are some real-life examples of kinetic energy?

Some examples of kinetic energy in everyday life include a moving car, a thrown ball, a swinging pendulum, and a running person. Essentially, any object that is in motion possesses kinetic energy.

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