Q165 / 225 · JEE Main 2003 · Physics
When a $U^{238}$ nucleus originally at rest, decays by emitting an alpha particle having a speed ' $u$ ', the recoil speed of the residual nucleus is
- Correct answerA$\frac{4 \mathrm{u}}{238}$
- B$-\frac{4 \mathrm{u}}{234}$
- C$\frac{4 \mathrm{u}}{234}$
- D$-\frac{4 \mathrm{u}}{238}$
Solution
Applying the principle of conservation of linear momentum
(4) $(\mathrm{u})=(\mathrm{v})(238) \Rightarrow \mathrm{v}=\frac{4 \mathrm{u}}{238}$
Hence, the correct answer is option: 'A'.