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7. gravitation — Physics STD 11 Science — Question

Rajasthan BoardEnglish MediumSTD 11 SciencePhysics7. gravitation1 Mark
MCQ
The angular velocity of the earth at present in $\omega $ . With what angular velocity should it rotate so that weight of body at the equator appears to be zero ? ....... $\omega $
  • A
    $2$
  • B
    $8$
  • ✓
    $17$
  • D
    $289$
✓

Answer

Correct option: C.
$17$
c
The present value of angular velocity

$=\frac{2 \pi}{86400}=1.2 \times 10^{-3}$ rad/sec. $A$ body at

equator appears weightless if weight provides centripetal force,

i.e., $m \omega^{2} r=m g$

Or $\omega=\sqrt{\frac{g}{r}}=\sqrt{\frac{9.8}{6.4 \times 10^{6}}}$ rad/sec.

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