Question

8 The brake shoe and steel drum of a car continuously absorb 75 W as the car slows down. Assume a total outside surface area of 0.1 m2 with a convective heat transfer coefficient of 10 W/m2 K to the air at 20◦C. How hot does the outside brake and drum surface become when steady conditions are reached?

Answer 1

The surface temperature of the brake shoe and drum is 95°C.

Step-by-step explanation:

Given that,

Rate of heat = 75 W

Surface area = 0.1 m²

Heat transfer coefficient = 10 W/m²

Temperature = 20°C

We need to calculate the surface temperature of the brake shoe and drum

Using equation of heat

`Q=hAdT`

`Q=hA(T_(sur)-T_(air))`

Put the value into the formula

`75=10*0.1(T_(s)-20)`

`T_(sur)=(75)/(10*0.1)+20`

`T_(sur)=95^(\circ)C`

Hence, The surface temperature of the brake shoe and drum is 95°C.