9 6 pts The pipe is towed at U 2 ms and the boundary layer i

9. (6 pts.) The pipe is towed at U 2 m/s and the boundary layer is tripped at the leading edge. What is the power required to tow the pipe? A. 28.7 W B. 69.2 W C. 114.6 W D. 57.3 W E. none of the above

Solution

Write the equation for the drag force required to tow the pipe

F_D = C_D*A*(V² /2 )

Here C_D is the drag coefficient, A is the area and V is the velocity

Substitute C_D = 0.9 , A = (40)²/4, = 998.2 kg/m³, and V = 2 m/s

F_D = (0.9)*((40)²/4)*((998.2 kg/m³)(2)²/2 )

= 225.78 N

Write the equation for the power required to tow the pipe

W_D = F_D*V

Substitute F_D = 225.78 N and V = 2 m/s

W_D = (225.78 N)*(2 m/s)

= 451.56 W Answer

Hence option E is correct.