Question:

A solid sphere of mass \(2\,kg\) rolls on a horizontal surface at \(10\,m/s\) and then rolls up a \(30^\circ\) incline. The maximum height reached is:

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Rolling body \(\Rightarrow\) include rotational KE.
Updated On: Apr 16, 2026
  • \(10\,m\)
  • \(4.9\,m\)
  • \(14.2\,m\)
  • \(7.1\,m\)
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The Correct Option is D

Solution and Explanation

Concept: Total energy = translational + rotational: \[ E = \frac{1}{2}mv^2 + \frac{1}{2}I\omega^2 \] For solid sphere: \[ I = \frac{2}{5}mr^2,\quad \omega = \frac{v}{r} \]

Step 1:
Total energy.
\[ E = \frac{1}{2}mv^2 + \frac{1}{5}mv^2 = \frac{7}{10}mv^2 \]

Step 2:
Convert to potential energy.
\[ mgh = \frac{7}{10}mv^2 \] \[ h = \frac{7v^2}{10g} = \frac{7 \cdot 100}{10 \cdot 9.8} = 7.1\,m \]
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