Project ForgeMachine Design
Design Against Static Load
GATE 2020
Medium
A helical spring has spring 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
- Ak/2
- k
- C8k
- D16k
Explanation
k=Gd⁴/(8D³N). Doubling d, D, and N: k′=G(2d)⁴/[8(2D)³(2N)]=G×16d⁴/[8×8D³×2N]=(16/16)×Gd⁴/(8D³N)=k. The spring constant is unchanged.
Source: GATE ME 2020 Session 2 (ME-2) (2020)
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