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

Answer:

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

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

$75=10\times0.1(T_{s}-20)$

$T_{sur}=\dfrac{75}{10\times0.1}+20$

$T_{sur}=95^{\circ}C$

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