During frequent braking under race conditions the disk brake rotors on the car described above reach a temperature of 500C. These disk brakes rely on forced convection to cool them. The dimensions of each disk rotor are: outer radius 130mm; inner radius 50mm; thickness 10mm. (Assume the disk is a simple donut shape ).
i) What is the surface area of the disk rotor (in m2)? (Include both sides and the edges)
ii) Given the heat transfer of the disk rotor is 120 W/m2/K, how much heat energy is radiatred from each of the disk rotors when the ambient air temperature is 30 C