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The potential energy of a particle of mass m free to move along the x-axis is given by U = \frac{1}{2}kx^{2}for x < 0 and U = 0 for x \geq 0 (x denotes the x-coordinate of the particle and k is a positive constant). If the total mechanical energy of the particle is E, then its speed at x = -\sqrt{\frac{2E}{k}} is

Option: 1

zero


Option: 2

\sqrt{\frac{2E}{m}}


Option: 3

\sqrt{\frac{E}{m}}


Option: 4

\sqrt{\frac{E}{2m}}


Answers (1)

best_answer

 

If only conservative forces act on a system, total mechnical energy remains constant -

K+U=E\left ( constant \right )

\Delta K+\Delta U=0

\Delta K=-\Delta U

-

 

 

From the conservation of energy 

            K.E. + P.E. = E or     K.E = E - \frac{1}{2}kx^{2}

\therefore K.E \ at \ x= -\sqrt{\frac{2E}{k}} is

KE=E - \frac{1}{2}k\left ( \frac{2E}{k} \right ) = 0

\therefore The speed of particle at x =  - \sqrt{\frac{2E}{k}} is zero.

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Nehul

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