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MHT CET 2025 (25 Apr, Shift 1) · Critical Speed & Looping

Critical Speed & Looping question from MHT CET 2025 (25 Apr, Shift 1)

Q5MHT CET 2025 · 25 APR · SHIFT 1Medium

Critical Speed & Looping

A point mass ' mm ' attached at one end of a massless, inextensible string of length ' ll ' performs a vertical circular motion and the string rotates in vertical plane, as shown in the diagram. The increase in the centripetal acceleration of the point mass when it moves from point A to point C is [ g=g = acceleration due to gravity.]

Figure

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Answer: (b)

  1. From the figure, A is the top and C is at the level of O, so C is ll below A.
  2. Energy: vC2=vA2+2glv_C^2 = v_A^2 + 2gl
  3. Increase in ac=vC2−vA2l=2gll=2ga_c = \frac{v_C^2 - v_A^2}{l} = \frac{2gl}{l} = 2g
  4. So the answer is (b) 2 g.
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