Spring energy and work – Rankers Physics

Potential Energy & Equilibrium: Practice Problem & Solution

Assertion (A): If a spring is compressed, energy is stored in spring and when it is elongated, energy is released. Reason (R): Work done by spring force is equal to change in potential energy of the spring.  
Both (A) & (R) are true and the (R) is the correct explanation of the (A)
Both (A) & (R) are true but the (R) is not the correct explanation of the (A)
(A) is true but (R) is false
Both (A) and (R) are false

Short Solution (Best for NEET):

To solve this problem, we apply the core principles of Potential Energy & Equilibrium. Understanding the underlying formula is key to arriving at the correct answer below:

Elastic potential energy `\(U = \frac{1}{2} k x^2\)` is stored in a spring when it is compressed or elongated. Energy is released when the spring moves towards its equilibrium position, not during elongation itself. Thus, assertion (A) is false. For a conservative force like spring force, `\(W = -\Delta U\)`, so work done by spring force is equal to the negative of the change in potential energy.

Thus, reason (R) is also false. Both assertion and reason are false.

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