Q. A bob of mass 0.450 kg hangs from the massless string of a long simple pendulum. A bullet of mass 0.50 kg is fired vertically from below into the bob. The bullet gets embedded into the bob and the combination rises vertically through a height of 1.8 m. If $g = 10\ ms^{- 2}$, then the velocity of the bullet is
A) 6 ${ms}^{- 1}$
B) 60 ${ms}^{- 1}$
C) 600 ${ms}^{- 1}$
D) 6000 ${ms}^{- 1}$
Explanation
(b) $0.05v = (0.450 + 0.05)V$
or $V = \frac{0.05}{0.50}v = \frac{v}{10}$
Using $v^{2} - u^{2} = 2as$, we get
$0^{2} - \left( \frac{v}{10} \right)^{2} = - 2 \times 10 \times 1.8$
or $\left( \frac{v}{10} \right)^{2} = 36$ or $v = 60\ ms^{- 1}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.