Potential energy of a spring at increased stretch – Rankers Physics

Potential Energy & Equilibrium: Practice Problem & Solution

When a long spring is stretched by \(2\text{ cm}\), its potential energy is \(U\). If the spring is stretched by \(10\text{ cm}\), the potential energy stored in it will be: (2003)
\(U/5\)
\(5U\)
\(10U\)
\(25U\)

Solution Explained:

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:

Concept: Potential energy stored in a spring. Formula: \(PE = \frac{1}{2}kx^2\). Potential energy is proportional to the square of the extension (\(PE \propto x^2\)). Given \(PE_1 = U\) for \(x_1 = 2\text{ cm}\). We need \(PE_2\) for \(x_2 = 10\text{ cm}\). \(\frac{PE_2}{PE_1} = \left(\frac{x_2}{x_1}\right)^2 = \left(\frac{10\text{ cm}}{2\text{ cm}}\right)^2 = (5)^2 = 25\). Thus, \(PE_2 = 25U\).

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