Types of Collision

What physical quantities are involved prior to the collision?

• Kinetic Energy only.

• Momentum only.

• Kinetic Energy and Momentum.

How do we categorize the collisions?

• Based on Momentum only.

• Based on Kinetic Energy only.

• Based on both Kinetic Energy and Momentum.

Define Elastic Collision?

• If both Momentum and the Kinetic Energy of the objects before and after the collision remains the same in a defined system, then the collision is said to be an Elastic Collision.

• If Momentum is conserved but the Kinetic Energy of the objects before and after the collision is not conserved, then the collision is said to be an Elastic Collision.

Define Inelastic Collision?

• If Momentum is conserved but the Kinetic Energy of the objects before and after the collision does not remain the same in a defined system, then the collision is said to be an Inelastic Collision.

• If Momentum not conserved but the Kinetic Energy of the objects before and after the collision does not remain the same in a defined system, then the collision is said to be an Inelastic Collision.

Define Perfectly Inelastic Collision?

• Momentum is Conserved, big amount of Kinetic Energy is lost but objects stick together.

• Momentum is Conserved, big amount of Kinetic Energy is lost but objects get separated.

Think about two situations, one in which a player
catches a ball and another in which the ball bounces off her arm. Which collision is
perfectly inelastic? Explain why more kinetic energy is lost in one case than in the
other case.

• The situation in which the player catches the ball is Perfectly Inelastic. More kinetic energy is lost when the player catches the ball because the ball loses all its kinetic energy when it comes to a stop.

• The situation in which the ball bounces off is Perfectly Inelastic. More kinetic energy is lost when the player catches the ball because the ball loses all its kinetic energy when it comes to a stop.

A metal pendulum swings toward the right to hit a stationary wooden block. After the collision, the
block is dented and moves with a constant speed towards the right.
The pendulum bounces back to the left. Classify the collision.

• The collision is Inelastic because the block is dented pendulum bounces back.

• The collision is Elastic because the pendulum bounces back.

Two hockey players collide. Their pads are tangled, so
they do not move apart after the collision. What is the best classification for this
collision?

• It is a Perfectly Inelastic Collision because the players do not separate after the collision.

• It is a Perfectly Elastic Collision because their pads are tangled.