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!

The paradox of lost energy details below?

  1. Jan 23, 2013 #1
    Imagine two bodies A & B. they have same mass and same speed, but they are travelling in different direction. the kinetic energies of both the bodies is equal (1/2*mv^2), because they have same speed and mass. now they collide each other. As they have same mass and speed they both stop. now the kinetic energy of both the bodies is zero. but where is the kinetic energy gone......in other words what is it transformed into. but what about law of conservation of energy??
  2. jcsd
  3. Jan 23, 2013 #2


    User Avatar

    Staff: Mentor

    Welcome to PF!

    Some is absorbed due to the physical deformation and some is released as heat and sound.
  4. Jan 23, 2013 #3

    Doc Al

    User Avatar

    Staff: Mentor

    Don't confuse general energy conservation--which includes all forms of energy--with special cases where mechanical energy may be conserved. Total energy is always conserved, but only in special cases will kinetic energy be conserved in a collision, making it a perfectly elastic collision.
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Similar Discussions: The paradox of lost energy details below?
  1. Paradox of energy gain (Replies: 17)