A particle slides down along an inclined plane $A C$. If the plane is frictionless, kinetic energy of…

A particle slides down along an inclined plane $A C$. If the plane is frictionless, kinetic energy of particle at $C$ is
  1. $m g y$
  2. $m g x$
  3. $m g\left(\frac{y}{\sin \theta}\right)$
  4. $m g\left(\frac{y}{\cos \theta}\right)$

Solution

Let the mass of the particle be $m$. If the particle slides from height $y$ under the action of gravity, the velocity acquired by the particle is given by, $v=\sqrt{2 g y}$ Hence, kinetic energy, $\mathrm{KE}=\frac{1}{2} m v^2$ $ \begin{aligned} & \Rightarrow \quad \mathrm{KE}=\frac{1}{2} m(\sqrt{2 g y})^2 \\ & =m g y \\ & \end{aligned} $

Asked in: AP EAMCET 2021 (25 Aug Shift 1)

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