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MHT CET · Physics · Center of Mass Momentum and Collision

Three identical metal balls each of radius ' \(r\) ' are placed such that an equilateral triangle is formed when centres of three ball are joined. The centre of mass of the system is located at

  1. A centre of one of the balls.
  2. B point of intersection of medians.
  3. C line joining centres of any two balls.
  4. D on the circumference of any one of the balls.
Verified Solution

Answer & Solution

Correct Answer

(B) point of intersection of medians.

Step-by-step Solution

Detailed explanation

Balls are identical and of same radius, so volume and density of balls are the same.
\(\therefore \quad\) Masses of the ball will be same
\(\begin{aligned}
& \mathrm{X}_{\mathrm{cm}}=\frac{\mathrm{mx}_1+\mathrm{mx}_2+\mathrm{mx}_3}{\mathrm{~m}+\mathrm{m}+\mathrm{m}}=\frac{\mathrm{x}_1+\mathrm{x}_2+\mathrm{x}_3}{3} \\
& \mathrm{Y}_{\mathrm{cm}}=\frac{\mathrm{my}_1+\mathrm{my}_2+\mathrm{my}_3}{\mathrm{~m}+\mathrm{m}+\mathrm{m}}=\frac{\mathrm{y}_1+\mathrm{y}_2+\mathrm{y}_3}{3}
\end{aligned}\)
\(\mathrm{X}_{\mathrm{cm}}, \mathrm{Y}_{\mathrm{cm}}\) is the centroid of the equilateral triangle.