JEE PHYSICS MCQ: GRAVITATION

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A diametrical tunnel is dug across the earth. A ball is dropped into the tunnel from one earth. A ball is dropped into the tunnel from one side. The velocity of the ball when it reached the centre of the earth is (Given: gravitational potential at the centre of earth

= - \frac{3}{2}\,\left( {\frac{{GM}}{R}} \right)

)

View answer and explanation

Correct option: B

\sqrt {gR}

Option B (

\sqrt {gR}

) is correct because it is derived from equating the loss in potential energy to the gain in kinetic energy as the ball moves to the center of the Earth.

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The escape velocity for a body projected vertically upwards from the surface of the earth is

11.2\mathrm{\;\;km}{\mathrm{s}^{ - 1}}

. If the body is projected in a direction making an angle of

{45^0}

with the vertical, the escape velocity will be The escape velocity of a body projected from the surface of earth is

v_e

. If the body is projected at an angle

\theta

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