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: How much does a car's disk breaks heat up when,

  1. Sep 9, 2011 #1
    Imaging a car decelerating from 120km/h to 80km/h. How much do the disk breaks heat up if 50% of the energy translates directly as heat (to the breaks). The car's mass is 1300kg and the full mas of the disk breaks are 11kg. The disks are made of steel Q=0.46 (heat capacity)

    I've been using Ke formula and Q=cm¤T

    ¤ stands for ''difference in''. Not sure what the correct notation is.
  2. jcsd
  3. Sep 9, 2011 #2


    User Avatar
    Gold Member

    so you use the ke formula so find out the energy lost, you know that 50% of it translates to heat.

    the other equation:
    [tex] Q = cm \Delta T [/tex]

    Q is the heat energy that went into the break, c is the heat capacity, m is the mass of the disk, and [itex] \Delta T [/itex] is the change in temperature of the break
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook