COMEDK · Physics · 7. Center of Mass Momentum and Collision
From a circular disc of radius 2 R , a smaller circular disc is cut with radius of the larger disc as its diameter. The centre of the hole is at a distance of \(R\) from the centre of the original disc. The distance of the centre of mass of the remaining portion from the centre is:
- A \(\dfrac{R}{3}\)
- B \(\dfrac{R}{2}\)
- C \(\dfrac{R}{4}\)
- D \(\dfrac{R}{6}\)
Answer & Solution
Correct Answer
(A) \(\dfrac{R}{3}\)
Step-by-step Solution
Detailed explanation
Let the radius of the original disc be \(r_1 = 2R\). The area of the original disc is \(A_1 = \pi (2R)^2 = 4\pi R^2\). The smaller disc cut from it has a diameter equal to the radius of the larger disc, so its diameter is \(2R\) and its radius is \(r_2 = R\). The area of the…
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