A 1500 kg car, travelling at 108 km/hr, is pulled over in an 80 km/hr zone. What is the temperature rise in each of the four brake drums? (Each of the four iron brake drums weigh 8.0 kg and the specific heat of iron is 448 J/kg/°C.)
My attempt:
v2-u2 = 2ad
a = (v2-u2)/2d
F = ma = m/(2d) * (v2-u2)
W = Fd = m/(2d) * (v2-u2) * d = m/2 * (v2-u2)
Q = mc(Tf-Ti)
Tf-Ti = Q/(mc) = W/(mc) = m/2 * (v2-u2) * 1/(mc) = (v2-u2)/(2c)
v = 108 km/hr = 30 m/s, u = 0 (since it comes to a stop), c = 448 J/kg/°C
So Tf-Ti = 302/(2*448) = 1.0
This answer is wrong though. Any help would be appreciated.