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

1. Sep 9, 2011

### Northener

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. Sep 9, 2011

### wukunlin

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

the other equation:
$$Q = cm \Delta T$$

Q is the heat energy that went into the break, c is the heat capacity, m is the mass of the disk, and $\Delta T$ is the change in temperature of the break