1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: True or False

  1. Mar 30, 2004 #1
    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. jcsd
  3. Mar 30, 2004 #2


    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

  4. Mar 30, 2004 #3
    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?

  5. Mar 31, 2004 #4


    User Avatar
    Science Advisor
    Homework Helper

    In the context of your posts 'at rest' is poorly defined - does the excercise specify a reference frame?
  6. Mar 31, 2004 #5
    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.
  7. Mar 31, 2004 #6
    That's not quite right. More than just 1 of them is true.

Share this great discussion with others via Reddit, Google+, Twitter, or Facebook