If the Earth has no rotational motion, the weight of a person on the equator is \({W}.\) Determine the speed with which the Earth would have to rotate about its axis so that the person at the equator will weigh \(\frac{3}{4}W.\) 
(The radius of the Earth is \(6400~\text{km}\) and \({g}=10~\text{m/s}^2)\)
1. \(0.28\times10^{-3}~\text{rad/s}\)
2. \(1.1\times10^{-3}~\text{rad/s}\)
3. \(0.83\times10^{-3}~\text{rad/s}\)
4. \(0.63\times10^{-3}~\text{rad/s}\)
Subtopic:  Acceleration due to Gravity |
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The value of acceleration due to gravity at Earth’s surface is \(9.8~ \text {ms}^{-2}.\) The altitude above its surface at which the acceleration due to gravity decreases to \(4.9~ \text {ms}^{-2},\) is close to:
(Radius of earth = \(6.4 \times 10^6 ~\text m\)
1. \(6.4 \times 10^6~ \text m\)
2. \(9.0 \times 10^6~ \text m\)
3. \(2.6 \times 10^6~ \text m\)
4. \(1.6 \times 10^6 ~\text m\)
Subtopic:  Acceleration due to Gravity |
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The height '\(h\)' at which the weight of a body will be the same as that at the same depth '\(h\)' from the surface of the earth is (Radius of the earth is \(R\) and effect of the rotation of the earth is neglected) :
1. \( \frac{\sqrt{5} R-R}{2} \)
2. \( \frac{\sqrt{5}}{2} R-R \)
3. \( \frac{R}{2} \)
4. \( \frac{\sqrt{3} R-R}{2}\)

Subtopic:  Acceleration due to Gravity |
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The value of the acceleration due to gravity is \(g_1\) at a height \(h=\frac{R}{2}\) (\(R\) = radius of the earth) from the surface of the earth. It is again equal to \(g_1\) at a depth \(d\) below the surface of the earth. The ratio \(\frac{d}{R}\) equals:
1. \( \frac{7}{9} \)
2. \( \frac{4}{9} \)
3. \( \frac{1}{3} \)
4. \( \frac{5}{9} \)

Subtopic:  Acceleration due to Gravity |
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A body weighs \(49\) N on a spring balance at the north pole. What will be its weight recorded on the same weighing machine, if it is shifted to the equator? (use \(g=\frac{GM}{R^2}=9.8~\mathrm{ms^{-2}}\) radius of earth, \(R=6400\) km.]
1. \(49~\mathrm{N}\)
2. \(48.83~\mathrm{N}\)
3. \(49.83~\mathrm{N}\)
4. \(49.17~\mathrm{N}\)

Subtopic:  Acceleration due to Gravity |
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In the reported figure of earth, the value of acceleration due to gravity is same at point \(A\) and \(C\) but it is smaller than that of its value at point B (surface of the earth). The value of \(OA:OB\) will be:

  
1. \(4:5 \)
2. \(5:4\)
3. \(2:3\)
4. \(3:2\)

Subtopic:  Acceleration due to Gravity |
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The approximate height from the surface of the earth at which the weight of the body becomes \(1 \over 3\) of its weight on the surface of the earth is: [Radius of earth \(R = 6400\) km and \(\sqrt{3}= 1.732\)]
1. \(3840\) km
2. \(4685\) km
3. \(2133\) km
4. \(4267\) km
Subtopic:  Acceleration due to Gravity |
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The height of point \(P\) above the surface of the earth is equal to the diameter of the earth. The value of acceleration due to gravity at point \(P\) will be: (Given \(g\) = acceleration due to gravity at the surface of the earth)
1. \(\dfrac{g}{2}\)
2. \(\dfrac{g}{4}\)
3. \(\dfrac{g}{3}\)
4. \(\dfrac{g}{9}\)
Subtopic:  Acceleration due to Gravity |
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The variation of acceleration due to gravity \((g)\) with distance \((r)\) from the center of the earth is correctly represented by: (Given \(R=\) radius of the earth)
1.   2.
3. 4.
Subtopic:  Acceleration due to Gravity |
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An object is taken to a height above the surface of earth at a distance \({5 \over 4}R\) from the centre of the earth. Where radius of earth, \(R= 6400\) km. The percentage decrease in the weight of the object will be: 
1. \(36\%\) 
2. \(50\%\)
3. \(64\%\)
4. \(25\%\)
Subtopic:  Acceleration due to Gravity |
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