A nuclide at rest emits an alpha-particle. In this process:

Options

A. alpha-particle moves with large velocity and the nuclesus remains at rest
B. both alpha-particle and nucleus move with equal speed in opposite direction
C. both move in opposite direction but nucleus with greater speed
D. both move in opposite direction but alpha-particle with greater speed.

Answer

D

Explanation

As `F_(ext)=0` , hence `vec(P)_(s)` =constant
or `vec(P)_(alpha)+vec(P)_(N)` =constant
Because nuclide was at rest brfore emission of alpha particle, hence acording to law of conservation of momentum `vec(P)_(alpha)+vec(P)_(N)=0` .
or `m_(alpha)vec(v)_(alpha)+m_(N)vec(v)_(N)=0` or `vec(v)_(alpha)=-(m_(N))/(m_alpha)vec(v)_(N)` .
Thus, alpha-particle and the nuncleus move in opposite directions. Further, as `m_(N)gtgtm_(oo)` hence `v_(alpha)gtgtv_(N)` .