1. Not finding help here? Sign up for a free 30min 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!

Kinetic energy problem

  1. Apr 16, 2007 #1
    1. The problem statement, all variables and given/known data
    Is is possible to have a change in kinetic energy without providing an external force.

    2. Relevant equations

    3. The attempt at a solution

    I want some examples of the above mentioned problem. In radio active decay the alpha particles are coming out from the nucleus with a kinetic energy but we have not given any external force. is this example correct?
  2. jcsd
  3. Apr 16, 2007 #2


    User Avatar
    Science Advisor
    Homework Helper

    KE=(1/2)*m*v^2. The acceleration of a body without an external force is zero. Put the two together. In the example of radioactive decay the particle tunnels out of the nucleus. In this case are you correct is saying that the alpha particle had zero kinetic energy before doing this? (Consider the uncertainty principle).
  4. Apr 16, 2007 #3
    When a stationary thing explodes?
    Initially it does not have kinetic energy, but once its particles started moving in different directions..so net kinetic energy becomes more than 0.

    I think you just need to identify a source of potential energy in a system, it is exists then that energy can be converted to kinetic energy
  5. Apr 16, 2007 #4
    mass is a form of potential energy right?
    Last edited: Apr 16, 2007
  6. Apr 17, 2007 #5


    User Avatar
    Science Advisor
    Homework Helper

    Possibly. If you define 'external' other than as its definition in the second law.
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?

Similar Discussions: Kinetic energy problem
  1. Kinetic Energy Problem (Replies: 5)