# A football, meant to be thrown at $100 \mathrm{~km} / \mathrm{h}$ in sea level air $\left(\rho=1.22 \mathrm{~kg} / \mathrm{m}^{3}, \mu=1.78 \times 10^{-5} \mathrm{~N}-\mathrm{s} / \mathrm{m}^{2}\right),$ is to be tested using a one-quarter scale model in a water tunnel $\left(\rho=1000 \mathrm{~kg} / \mathrm{m}^{3}, \mu=10^{-3} \mathrm{~N}-\mathrm{s} / \mathrm{m}^{2}\right)$. For dynamic similarity, the ratio of the model force to the prototype force is ______________(round to nearest integer).

## Question ID - 1 :- A football, meant to be thrown at $100 \mathrm{~km} / \mathrm{h}$ in sea level air $\left(\rho=1.22 \mathrm{~kg} / \mathrm{m}^{3}, \mu=1.78 \times 10^{-5} \mathrm{~N}-\mathrm{s} / \mathrm{m}^{2}\right),$ is to be tested using a one-quarter scale model in a water tunnel $\left(\rho=1000 \mathrm{~kg} / \mathrm{m}^{3}, \mu=10^{-3} \mathrm{~N}-\mathrm{s} / \mathrm{m}^{2}\right)$. For dynamic similarity, the ratio of the model force to the prototype force is ______________(round to nearest integer).

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Answer Key : (4 to 4) -

4 to 4

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