A) \[4.8\times {{10}^{5}}N,\] downwards
B) \[4.8\times {{10}^{5}}N,\]upwards
C) \[2.4\times {{10}^{5}}N,\]upwards
D) \[2.4\times {{10}^{5}}N,\] downwards
Correct Answer: C
Solution :
Applying Bernoulli's theorem just above and just below the roof, \[P+\frac{1}{2}\rho {{v}^{2}}={{P}_{0}}+0\] \[({{P}_{0}}-P)=\frac{1}{2}\rho {{v}^{2}}=\Delta P\] Hence lift of the roof \[F=\Delta P.A=\frac{1}{2}\rho A{{v}^{2}}\] \[=\frac{1}{2}\times 1.2\times {{(40)}^{2}}\times 250=2.4\times {{10}^{5}}N\]You need to login to perform this action.
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