Question

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
• D. 1.5

Answer 1

Answer: (C)

0.5

Answer 2

The correct answer is (C): 0.5
S = 4 cm
$v'_4 = \frac{v}{3}, a = \text constant$
$v_{4+x} = 0$
$(v^2-\frac{v^2}{a}) = 2a(4)$
$(v^2-0) = 2a(4+x)$
$\frac{4}{4+x} = \frac{8}{9}$
$⇒ x = 0.5m$