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JEE Main 2021 (17 Mar, Shift 2) · Continuous Bodies: Standard Results & Variable Density

Continuous Bodies: Standard Results & Variable Density question from JEE Main 2021 (17 Mar, Shift 2)

Q4JEE Main 2021 · 17 MAR · SHIFT 2Medium

Continuous Bodies: Standard Results & Variable Density

The disc of mass M with uniform surface mass density σ\sigma is shown in the figure. The centre of mass of the quarter disc (the shaded area) is at the position x3aπ,x3aπ\frac{x}{3}\frac{a}{\pi}, \frac{x}{3}\frac{a}{\pi} where x is _____________. (Round off to the Nearest Integer).

[a is an area as shown in the figure]

Figure

Numerical answer type. Work it out, then open the answer.

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Answer: 4

  1. In the figure aa is the radius of the disc.
  2. For a uniform quarter disc of radius aa, xcm=ycm=4a3πx_{cm} = y_{cm} = \frac{4a}{3\pi}.
  3. Comparing with x3aπ\frac{x}{3}\frac{a}{\pi}: x=4x = 4
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