Of course they are needed because without them the society wouldn’t be as nice as it is right now and plus there would be no more buildings ! :)
Complete Question
Air at 40C flows over a 2 m long flat plate with a free stream velocity of 7m/s. Assume the width of the plate (into the paper) is 0.5 m. If the plate is at a co temperature of 100C,find:
The total heat transfer rate from the plate to the air
Answer:

Explanation:
From the question we are told that:
Air Temperature 
Length 
Velocity 
Width 
Constant temperature 
Generally the equation for Total heat Transfer is mathematically given by

Where
h=Convective heat transfer coefficient

Therefore




Answer:
c
Explanation:
This is because many things, such as pcs, over heat