A body is executing simple harmonic motion. At a displacement ' $x$ ' its potential energy is, $E_1$ and at…

A body is executing simple harmonic motion. At a displacement ' $x$ ' its potential energy is, $E_1$ and at a displacement ' $y$ ' its potential energy is $E_2$, The potential energy E at a displacement $(x+y)$ is
  1. $\sqrt{E}=\sqrt{E_1}-\sqrt{E_2}$
  2. $\sqrt{E}=\sqrt{E_1}+\sqrt{E_2}$
  3. $E_1=E_1-E_2$
  4. $E_1=E_1+E_2$

Solution

For a body executing SHM, $\begin{aligned} & E_1=\frac{1}{2} k x^2, E_2=\frac{1}{2} k y^2 \\ & \therefore E=\frac{1}{2} k(x+y)^2=\frac{1}{2} k\left(x^2+y^2+2 x y\right) \\ & =\frac{1}{2} k x^2+\frac{1}{2} k y^2+2\left[\frac{1}{2} k(\sqrt{x y})^2\right] \\ & =E_1+E_2+2 \sqrt{E_1 E_2}=\left(\sqrt{E_1}+\sqrt{E_2}\right)^2 \\ & \therefore \sqrt{E}=\sqrt{E_1}+\sqrt{E_2} \end{aligned}$

Asked in: AP EAMCET 2024 (21 May Shift 2)

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