question_answer

A bullet fired into a fixed target loses half of its velocity after penetrating 3 cm. How much further it will penetrate before coming to rest, assuming that it faces constant resistance to motion?     AIEEE  Solved  Paper-2005

A) 3.0 cm

B)                        2.0 cm  

C)        1.5 cm  

D)        1.0 cm

Correct Answer: D

Solution :

According to work-energy theorem, Case I When bullet is penetrating 3 cm where, F is resistive force andis initial speed. Case II Let the further distance travelled by the bullet before coming to rest is s.   \[-F(3+s)\,={{K}_{f}}-{{K}_{i}}=-\frac{1}{2}\,mv_{0}^{2}\] or       or             or