Shown in the figure is a hollow ice-cream cone (it is open at top). If its mass is M , radius of its top is…

Shown in the figure is a hollow ice-cream cone (it is open at top). If its mass is M, radius of its top is R and height, H, then its moment of inertia about its axis is

  1. MR22
  2. MR2+H24
  3. MH23
  4. MR23

Solution

It can be assumed as several parts of discs having different radius, so

  

I=dl=dmr2

From diagram

ry=tanθ=RH

r=RH·y

dm=ρπr2dy

From equation (i), (ii) and (iii)

I=MR22

Asked in: JEE Main 2020 (06 Sep Shift 1)

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