When a bullet is fired a target, its velocity dwecreases by half after penetrating 30 cm into it. The additional thickness it will penetrate before coming to rest is

Options

A. 30 cm
B. 40 cm
C. 10 cm
D. 50 cm

Answer

C

Explanation

Retardation (a) `(((V)/(2))^(2) - v^(2))/(2S) = (-3v^(2))/(8 xx 0.3)`
`S. = (0-((V)/(2))^(2))/(2a) = (-v^(2))/(4) xx (1)/(2) xx (8 xx 0.3)/(-3v^(2))`
` = 0.1 = 10 cm`