# True or False

1. Mar 30, 2004

### PhysicsPhun

A) If car 1 sticks to car 2, the final total kinetic energy of the car1-car2 system is less than the initial total kinetic energy of the two cars.
B) If car 1 sticks to car 2, the car1-car2 system must be at rest after the collision.
C) Suppose (for this statement only) that car 2 was NOT initially at rest, but was instead heading towards car 1 with equal (but opposite) momentum before the collision. After the collision, the cars must both be at rest.
D) If car 1 is much lighter than m2, and the collision is perfectly elastic, car 1 will continue heading to the right with nearly its original speed after the collision.
E) If the collision is elastic, car 1 must always come to a stop after the collision

Anyone have ideas on these?

2. Mar 30, 2004

### chroot

Staff Emeritus
3. Mar 30, 2004

A) If they stick together, it's an inelastic collision. What's a consequence (actually the definition) of an inelastic collision?

B) Conservation of momentum says...?

C) Conservation of momentum says...?

D) Which way did car 1 start out going? There's not enough information to answer it as it is.

E) Why would this be true?

4. Mar 31, 2004

### NateTG

In the context of your posts 'at rest' is poorly defined - does the excercise specify a reference frame?

5. Mar 31, 2004

### PhysicsPhun

A car, mass m1 moves to the right on a frictionless air track. It collides with a second car, mass m2, which is initially at rest. Which of the following statements are true?

That is the Base of the Question. I left that out sorry.

From the help you guys gave, I'm thinking that the first is the only true statement.

6. Mar 31, 2004