The velocity of the bullet becomes one third after it penetrates 4 cm in a wooden block. Assuming that bullet is facing a constant resistance during its motion in the block. The bullet stops completely after travelling at (4+x) cm inside the block. The value of x is:
(A)2.0
(B)1.0
(C)0.5✓ Correct
(D)1.5
Answer: (C)
Solution
Using v2=u2−2as, after 4 cm: (3V)2=V2−2a(4), giving a=9V2. When the bullet stops: 0=V2−2a(4+x). Substituting a: V2=2×9V2×(4+x), so 9=2(4+x), giving 4+x=4.5, hence x=0.5 cm.
JEE Main · 2022 · 27 Jul 2022 · Shift 2 · Single correct option