The drag force acting on the wall.
The drag force when the velocity is doubled.
Answer to Problem 59P
The drag force acting on the wall when velocity is
The drag force acting on the wall when velocity is
Explanation of Solution
Given information:
The wind velocity is
Write the expression for the Reynolds number.
Here, the velocity of flow is
Write the expression for the frictional coefficient.
Write the expression for the area of the wall.
Here, the length of the wall is
Write the expression for the drag force when the pressure drag is zero.
Here, the density of air is
Calculation:
Refer to Table A-9, “Properties of air” to obtain the values of
Substitute
The flow is laminar and turbulent as the obtained value of Reynolds number is greater than the critical Reynolds number.
Substitute
Substitute
Substitute
The velocity is doubled as stated.
Substitute
Substitute
Substitute
Conclusion:
The drag force acting on the wall when velocity is
The drag force acting on the wall when velocity is
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