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Strength of Materials
Stress & Strain
GATE 2021
Hard

A right solid circular cone standing on its base on a horizontal surface has height H and base radius R, specific weight w, and elastic modulus E. The vertical deflection at mid-height of the cone due to self-weight is given by

  • wH²/8E
  • BwH²/6E
  • CwRH/8E
  • DwRH/6E

Explanation

Measuring height y from the base, the axial stress at y is σ(y) = w×(volume of cone above y)/(area at y) = w×[(1/3)πr(y)²(H-y)]/[πr(y)²] = w(H-y)/3 — remarkably independent of the radius, since the taper cancels exactly. Strain ε(y)=σ(y)/E. Displacement at y (relative to the fixed base) = ∫₀^y ε dy' = (w/3E)[Hy-y²/2]. At y=H/2: u=(w/3E)[H²/2-H²/8]=(w/3E)(3H²/8)=wH²/(8E).

Source: GATE ME 2021 Session 1 (ME-1) (2021)

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