Physics B Collisions

Consider a perfectly inelastic head-on collision between a small car and a large truck traveling at the same speed. Which vehicle has a greater change in kinetic energy as a result of the collision?

Because the initial velocities of the truck and the car are the same and the final velocity is the same, the change in kinetic energy depends only on mass. The truck has a greater mass, so the change in its kinetic energy is greater.

Consider a perfectly inelastic head-on collision between a small car and a large truck traveling at the same speed. Which vehicle has a greater change in kinetic energy as a result?

Because the initial velocities of the truck and the car are the same and the final velocity is the same, the change in kinetic energy depends only on the mass. The truck has a greater mass, so the change in its kinetic energy is greater.

Examples of elastic collisions include:

Billiard balls colliding, soccer ball hitting a players foot, tennis ball hitting a wall.

If two objects collide and one is initially at rest, is it possible for both to be at rest after the collision?

Both cannot be at rest after the collision because the total initial momentum was greater than zero.

Given the masses of two objects and their velocities before and after a head-on collision, how could you determine whether the collision was elastic, inelastic or perfectly inelastic?

By calculating the kinetic energy before and after the collision; If KE is conserved, the collision is elastic. If the collision is not elastic, look at the final velocities to determine if it is perfectly inelastic.

Given the masses of two objects and their velocities before and after a head-on collision, how could you determine whether the collision was elastic, inelastic, or perfectly inelastic?

By calculating the kinetic energy before and after the collision; if the kinetic energy is conserved, the collision is elastic. If the collision is not elastic, look at the final velocities to determine if it is perfectly inelastic.

A person kicks a football. What type of collision is this?

Elastic

Two billiard balls collide. Identify the type of collision:

Elastic

Both momentum and kinetic energy are conserved in an:

Elastic collision.

In which type of collision is kinetic energy conserved? What is an example of this type of collision?

Elastic collision; Sample: Two billiard balls collide and then move separately after the collision.

Few collisions are:

Elastic or perfectly inelastic.

A tennis ball is dropped from 1 m, bounces off the ground and rises to 0.85 m. What kind of collision occurred between the ball and the ground?

Inelastic collision

A billiard ball collides with a stationary identical billiard ball in an elastic head-on collision. After the collision, which is true of the first ball?

It comes to a rest.

In an inelastic collision,

Kinetic energy is converted to internal elastic potential energy when the objects deform. Some kinetic energy is also converted to sound energy and internal energy.

In a two-body collision:

Momentum is conserved

Two playground balls collide in an inelastic collision:

Momentum is conserved, but kinetic energy is not conserved.

A rubber ball collides elastically with the sidewalk. Does each object have the same KINETIC energy after the collision as it had before the collision?

No, if the collision is perfectly elastic, the TOTAL kinetic energy is conserved, but each object can gain or lose kinetic energy.

If two automobiles collide, they usually do not stick together. Does this mean the collision is elastic?

No, some kinetic energy is converted to sound energy and heat energy and some is converted to internal elastic potential energy as the cars deform, so the collision cannot be elastic.

A rubber ball collides elastically with the sidewalk. Does each object have the same MOMENTUM after the collision as it has before the collision?

No, total momentum is conserved, but each object can gain or lose momentum.

In an elastic collision between two objects, do both objects have the same kinetic energy after the collision as before?

No; TOTAL kinetic energy is conserved, but kinetic energy can be TRANSFERRED from one object to the other.

In an elastic collision between two objects, do both objects have the same kinetic energy after the collision as before?

No; total kinetic energy is conserved but kinetic energy can be transferred from one object to another.

Which is NOT evidence that kinetic energy has been lost in a collision?

One of the objects is at rest after the collision.

Two balls of dough collide and stick together. What type of collision is this?

Perfectly inelastic

Two cars collide, lock bumpers, and move together after the collision. What kind of collision is this?

Perfectly inelastic

Two objects stick together and move with the same velocity after colliding. Identify the type of collision:

Perfectly inelastic

Momentum is conserved but kinetic energy is not conserved in a :

Perfectly inelastic collision

Examples of perfectly inelastic collisions include:

Person catching a ball, meteorite hitting earth, two clay balls colliding.

Why is the sound and heat produced by a collision evidence that the collision is not elastic?

Producing sound and heat requires energy. Because the system of objects loses some energy as sound and heat are produced in the collision, the total kinetic energy cannot be conserved, so the collision cannot be elastic.

When an inelastic material is in a collision:

Some of the work done to deform the material is converted to other forms of energy.

Which of the following best describes the kinetic energy of each object after a two-body collision if the momentum of the system is conserved?

The kinetic energy Might also be conserved.

Which of the following best describes momenta of two bodies after a two-body collision if the kinetic energy of the system is conserved?

The momenta must also be conserved.

In an elastic collision between two objects with unequal mass,

The momentum of one object will increase by the amount that the momentum of the other object decreases.

If two objects collide and one is initially at rest, is it possible for one to be at rest after the collision?

The object initially in motion can be at rest if it's momentum is entirely transferred to the other object.

Inelastic collision:

The two objects deform during the collision so that the total kinetic energy decreases, but the objects move separately after the collision.

Examples of inelastic collisions include:

Two cars colliding, changing form, and moving separately after the collision.

In an elastic collision,

Two objects return to their original shapes and move away from the collision separately.

In a perfectly inelastic collision,

Two objects stick together and move as one mass after the collision.

Two billiard balls of equal mass are traveling straight toward each other with the same speed. They meet head-on in an elastic collision. What is the total momentum of the system containing the two balls before the collision? What about after the collision?

Zero, zero

When an inelastic material is in a collision,

some of the work done to deform the material is converted to other forms of energy.

If two objects collide and one is initially at rest, Is it possible for one to be at rest after the collision?

the object initially in motion can be at rest if its momentum is entirely transferred to the other object.