Medium MCQ +4 / -1 PYQ · JEE Mains 2020

On the x-axis and at a distance x from the origin, the gravitational field due a mass distribution is given by ${{Ax} \over {{{\left( {{x^2} + {a^2}} \right)}^{3/2}}}}$ in the x-direction. The magnitude of gravitational potential on the x-axis at a distance x, taking its value to be zero at infinity, is:

  1. A ${A{{\left( {{x^2} + {a^2}} \right)}^{3/2}}}$
  2. B ${A{{\left( {{x^2} + {a^2}} \right)}^{1/2}}}$
  3. C ${A \over {{{\left( {{x^2} + {a^2}} \right)}^{1/2}}}}$ Correct answer
  4. D ${A \over {{{\left( {{x^2} + {a^2}} \right)}^{3/2}}}}$

Solution

Given ${E_x} = {{Ax} \over {{{({x^2} + {a^2})}^{3/2}}}}$<br><br>$\therefore$ ${{ - dV} \over {dx}} = {{Ax} \over {{{({x^2} + {a^2})}^{3/2}}}}$<br><br>$\Rightarrow$ $$\int\limits_0^V {dV} = - \int\limits_\infty ^x {{{Ax} \over {{{({x^2} + {a^2})}^{3/2}}}}dx} $$<br><br>$\Rightarrow$ $V = {A \over {{{({x^2} + {a^2})}^{1/2}}}}$

About this question

Subject: Physics · Chapter: Gravitation · Topic: Gravitational Field and Potential

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