3. Consider a hot automotive engine, which can be approximated as a 0.6 m high, 0.3 m

wide, and 0.9 m long rectangular block. The bottom surface of the block is at a temperature

of 90°C and has an emissivity of 0.9. The ambient air is at 23°C, and the road surface is

at 28°C. The fluid properties of air are determined at the film temperature and can be found

in the tables at the end of the tutorial.

a. Determine the rate of heat transfer from the bottom surface of the engine block by

convection and radiation as the car travels at a velocity of 60 km/h. [916W]

b. If the temperatures were measured with a thermometer accurate to the nearest 1°C,

what is the uncertainty in the resultant heat transfer rate?

(You may ignore the uncertainties when calculating your fluid properties). [+10W]

c. If the speedometer in the car is accurate to the nearest 2km/h, what is the

uncertainty in the result? [+11W]

[Uncertainties assumed as independent in all cases]