HELP PLEASE?!?!?!?! A 4.0 kg model train going right at 6 m/s bumps into a toy wagon moving in the same direction at 2.0 m/s. The model train has a final speed of 4.8 m/s, and the toy wagon has a final speed of 5.2 m/s, both tho the right. What is the mass of the toy wagon?
Consider rightward as the positive direction and round to two significant digits.

The total momentum in any closed system will remain constant.

When two or more objects collide, the collision does not change the

total momentum of the two objects.

Whatever momentum is lost by one object in the collision is gained

by the other. The total momentum of the system is conserved.

Newton’s Cradle!!

¡ psystem = m1v1 + m2v2

¡ The total momentum of the system before the collision equals

the total momentum of the system after the collision. Thus,

psystem = p’system

There are three types of collisions:

1. Elastic

2. Completely Inelastic *

3. Inelastic **

* We will deal with this situation

** We will NOT deal with this situation

§ When an object hits another object and bounce off each

other, the collision would be Elastic.

Formula

§ m1v1+ m2v2 = m1v1‘ + m2v2‘

§ Where v is the velocity before the collision and v‘ is the

velocities after the collision.

Elastic Collisions

Examples

1. Pools Balls

2. Car wreck when cars hit and bounce away from each other

3. Baseball and bat collision

Elastic Collision Examples

How will you know which situation occurred? If direction changes,

velocity will be negative

Elastic Collision Possibilities

§ When an object hits another object and sticks together, the

collision would be totally inelastic.

§ Since the objects stick together, they have the same final velocity.

Formula

§ m1v1 + m2v2 = (m1 + m2)vF

§ Where v (v1 and v2) is the initial velocity of the objects and vF is the

final velocity of the objects stuck together.

Totally Inelastic Collisions

1. Box cars coupling together

2. Tackling a football player

3. Car wreck in which the cars become stuck

Totally Inelastic Collisions Examples