Calculating Thermal Energy Dissipated from Brakes on a Descending Car

[Stryder_SW]

Homework Statement

Proper design of automobile braking systems must account for heat buildup under heaving braking. Calculate the thermal energy dissipated from brakes in a 1260-kg car that descends a 18.5° hill. The car begins braking when its speed is 102 km/h and slows down to a speed of 34 km/h in a distance of 0.51 km measured along the road.


I honestly have no idea how to do this.

 

[LowlyPion]

Think about how much potential energy as well as kinetic energy must be accounted for by the work of breaking over that distance.

 

[tiny-tim]

Hi Stryder_SW!

Virtually all the mechanical energy lost goes into heat (thermal energy), so …

Hint: use the work-energy theorem … work done by the brakes = mechanical energy lost. ​