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The speed of earth's rotation about its axis is \omega. Its speed increases to \mathrm{x} times to make the effective acceleration due to gravity equal to zero at the equator. Then \mathrm{\mathrm{x}} is
 

Option: 1

1


Option: 2

8.5


Option: 3

17


Option: 4

34


Answers (1)

best_answer

\mathrm{ \mathrm{g}_{\mathrm{e}}^{\prime}=\mathrm{g}-\mathrm{R} \omega^2 }

Let \mathrm{ \omega_1 } be the angular speed of earth's rotation so that \mathrm{ \mathrm{g}_{\mathrm{e}}^{\prime}=0 }

\mathrm{ 0=\mathrm{g}-\mathrm{R} \omega_1^2, \frac{\mathrm{R} \omega_1^2}{\mathrm{~g}}=1 }             ............(1)

\mathrm{ \text { also } \frac{\mathrm{R} \omega^2}{\mathrm{~g}}=\frac{6.4 \times 10^6}{9.8} \times\left(\frac{2 \pi}{24 \times 60 \times 60}\right)^2 }

\mathrm{ =\frac{1}{291} }                               ...........(2)

\mathrm{ \frac{(1)}{(2)} ; \frac{\omega_1^2}{\omega^2}=291 (17.02)^2 }

\mathrm{ \omega_1 \simeq \omega \times 17=\omega \times \mathrm{x} }

\mathrm{ \therefore \quad \mathrm{x}=17 \text {. } }

Hence option 3 is correct.






 

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vinayak

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