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JEE Advanced Physics Nuclear Physics 2022 JEE Advanced 2022 (Paper 1)

JEE Advanced Physics Question (2022) — Solution

Question

The minimum kinetic energy needed by an alpha particle to cause the nuclear reaction N 7 16 + He 2 4 → H 1 1 + O 8 19 in a laboratory frame is n  (in MeV ). Assume that N 7 16 is at rest in the laboratory frame. The masses of N 7 16 ,   He 2 4 ,   H 1 1 and O 8 19 can be taken to be 16 . 006   u ,   4 . 003   u , 1 . 008   u  and 19 . 003   u , respectively, where 1   u = 930   MeV   c - 2 . The value of n  is If the numerical value has more than two decimal places, truncate/round-off the value to TWO decimal places.

Options

  1. A. A
  2. B. B
  3. C. C
  4. D. D

Answer

A. A

Step-by-step solution

Given here:  N 7 16 + He 2 4 → H 1 1 + O 8 19 Energy absorbed in the reaction is  Q = m N + m He - m H - m O × c 2 = 16 . 006 + 4 . 003 - 1 . 008 - 19 . 003 × 930   MeV = - 1 . 86   MeV = 1 . 86   MeV   Let  v  is velocity of alpha particle. Now, the maximum loss of kinetic energy =   1 2 × m × 4 m 5 m × v 2 ⇒ 1 2 m v 2 = 5 4 × Q = 5 4 × 1 . 86   MeV = 2 . 325   MeV ∴   n = 2 . 33

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