A body of mass \(m\) is taken from the surface of earth to a height equal to twice the radius of earth \(\left(R_e\right).\) The increase in potential energy will be:
(\(g\) is acceleration due to gravity at the surface of earth) 
1. \(\dfrac{1}{2} m g R_e\)
2. \(\dfrac{3}{4} m g R_e\)
3. \(\dfrac{1}{4} m g R_e\)
4. \(\dfrac{2}{3} m g R_e\)
Subtopic:  Gravitational Potential Energy |
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Given below are two statements: 
Assertion (A): The kinetic energy needed to project a body of mass \(\text m\) from earth surface to infinity is \(\dfrac{mgR}{2},\) where \(R\) is the radius of earth.
Reason (R): The maximum potential energy of a body is zero when it is projected to infinity from earth surface.
In the light of the above statements, choose the correct answer from the options given below:
1. Both (A) and (R) are True and (R) is the correct explanation of (A).
2. Both (A) and (R) are True but (R) is not the correct explanation of (A).
3. (A) is True but (R) is False.
4. (A) is False but (R) is True.
Subtopic:  Gravitational Potential Energy |
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Three identical spheres of mass \(m, \) are placed at the vertices of an equilateral triangle of length \(a\). When released, they interact only through gravitational force and collide after a time \(T=4 \) seconds. If the sides of the triangle are increased to length \(2a\) and also the masses of the spheres are made \(2m,\) then they will collide after: (in seconds)
1. \(8\) 
2. \(19\) 
3. \(35\) 
4. \(27\)
Subtopic:  Gravitational Potential Energy |
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Match the following physical quantities related to the Earth–Sun system:
(Given: Mass of sun = \(M_s,\) Mass of earth =\(M_e,\) Radius of earth = \(R,\) Distance between sun and earth =\(a\))
\(\mathrm{(A)}\) The kinetic energy of the earth \(\mathrm{(I)}\) \(-\dfrac{G M_s M_e}{a}\)
\(\mathrm{(B)}\) The potential energy of the earth and the sun \(\mathrm{(II)}\) \(\dfrac{G M_s M_e}{2 a}\)
\(\mathrm{(C)}\) The total energy of the earth and the sun  \(\mathrm{(III)}\) \(\dfrac{G M_e}{R}\)
\(\mathrm{(D)}\) Escape energy from the surface of the earth per unit mass  \(\mathrm{(IV)}\) \(-\dfrac{G M_s M_e}{2 a}\)

Codes:
1. \(\mathrm{A\text-II,B\text-I,C\text- IV,D\text- III}\)
2. \(\mathrm{A\text-I,B\text-II,C\text- III,D\text- IV}\)
3. \(\mathrm{A\text-III,B\text-IV,C\text- I,D\text- II}\)
4. \(\mathrm{A\text-IV,B\text-III,C\text- II,D\text- I}\)
Subtopic:  Gravitational Potential Energy |
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A particle is released from a height equal to radius of earth, \(R.\) Its velocity when it strikes the ground is:
1. \(\sqrt{gR}\)

2. \(\sqrt{{{gR}\over{2}}}\)

3. \(\sqrt{2gR}\)

4. \(\sqrt{4gR}\)
Subtopic:  Gravitational Potential Energy |
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A particle is released at a height equal to the radius of the earth above the surface of the earth. Its velocity when it hits the surface of the earth is equal to:
(Where, \(M_e\)=mass of earth, \(R_e\)= radius of the earth.)
1. \(\sqrt{\left[{\frac{2{GM}_{e}}{{R}_{e}}}\right]}\)
2. \(\sqrt{\left[{\frac{{GM}_{e}}{2{R}_{e}}}\right]}\)
3. \(\sqrt{\left[{\frac{{GM}_{e}}{{R}_{e}}}\right]}\)
4. \(\sqrt{\left[{\frac{2{GM}_{e}}{3{R}_{e}}}\right]}\)
 
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An object of mass \(m\) is placed at a height \(R_{e}\) from the surface of the earth. What is the increase in potential energy of the object if the height of the object is increased to \(2R_{e}\) from the surface? (\(R_{e}:\) Radius of the earth)
1. \({\dfrac{1}{3}{mgR}_{e}}\)
2. \({\dfrac{1}{6}{mgR}_{e}}\)
3. \({\dfrac{1}{2}{mgR}_{e}}\)
4. \({\dfrac{1}{4}{mgR}_{e}}\)
Subtopic:  Gravitational Potential Energy |
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Four spheres, each of mass \(m,\) are placed at the corners of a square of side \(d.\) A fifth sphere of mass \(M\) is located at the centre of the square. What is the total gravitational potential energy of the system?
1. \( -\dfrac{{Gm}}{{d}}\left [(4+\sqrt{2}) {m}+4 \sqrt{2} {M} \right ] \)
2. \( -\dfrac{{Gm}}{{d}}\left [(4+\sqrt{2}) {M}+4 \sqrt{2} {m} \right ] \)
3. \( -\dfrac{{Gm}}{{d}}\left[3 {m}^2+4 \sqrt{2}{M}\right] \)
4. \(-\dfrac{{Gm}}{{d}}\left[6{m}^2+4 \sqrt{2}{M}\right]\)
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An object of mass \(1\) kg is taken to a height from the surface of the Earth which is equal to three times the Earth's radius. The gain in potential energy of the object will be:
(Given: \(g=10\) ms–2 and radius of Earth \(=6400\) km)
1. \(48\) MJ
2. \(24\) MJ
3. \(36\) MJ
4. \(12\) MJ
Subtopic:  Gravitational Potential Energy |
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A body is projected vertically upwards from the surface of the earth with a velocity equal to one-third of escape velocity. The maximum height attained by the body will be:
(take the radius of the Earth \(R=6400~\text{km}\) and \(g=10~\text{m/s}^2\) )
1. \(800~\text{km}\) 
2. \(1600~\text{km}\)
3. \(2133~\text{km}\)
4. \(4800~\text{km}\)
Subtopic:  Gravitational Potential Energy |
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