A sphere of mass 25 gram is placed on a vertical spring. Spring is compressed by $0.2 \mathrm{~m}$ using a…

A sphere of mass 25 gram is placed on a vertical spring. Spring is compressed by $0.2 \mathrm{~m}$ using a force $5 \mathrm{~N}$. When the spring is relaxed, mass is reaching a height of $\left(\mathrm{g}=10 \mathrm{~m} / \mathrm{s}^2\right)$
  1. $6 \mathrm{~cm}$
  2. $8 \mathrm{~cm}$
  3. $10 \mathrm{~cm}$
  4. $2 \mathrm{~m}$

Solution

Gravitational potential energy gained by the ball $=$ Elastic potential energy in the spring $\begin{aligned} & \mathrm{mgh}=\frac{1}{2} \mathrm{Fx} \\ & \therefore \mathrm{h}=\frac{\mathrm{Fx}}{2 \mathrm{mg}} \\ & =\frac{5 \times 0.2}{2 \times 25 \times 10^{-3} \times 10} \\ & =2 \mathrm{~m} \end{aligned}$

Asked in: MHT CET 2021 (21 Sep Shift 1)

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