Question

A helical spring has constant k. If the wire diameter, spring diameter and the number of coils are all doubled, then, the spring constant of the new spring becomes

• A. 8k
• B. 16k
• C. k
• D. k/2

Answer 1

The correct option is C k

As per given data: Spring constant,

$k_{\text{spring}}=\frac{G{d}^4}{8D^{3}n}$

Spring constant,
$k_{\text{new}}=\frac{G(2d{)}^4}{8\left(2D{)}^3\right(2n)}=\frac{G{d}^4}{8D^{3}n}$

$Hence,k_{\text{new}}=k$