Question

A police van moving on a highway with a speed of 30 km/h fires a bullet at a thief's car speeding away in the same direction with a speed of 192 km/h. If the nuzzle speed of the bullet is 150 m/s, with what speed does the bullet hit the thief's car?

• A. 105 m $s^{-1}$
• B. 110 m $s^{-1}$
• C. 115 m $s^{-1}$
• D. 120 m $s^{-1}$

Answer 1

The correct option is A

105 m $s^{-1}$

The speed of the bullet with respect to ground will be,

$v_{bg}$ = $v_{bv}$ + $v_{vg}$

=150 + $\frac{25}{3}$ = $\frac{475}{3}m{s}^{-1}$

Speed of thief's car is,

$v_{tg}$=192 $\times$ $\frac{5}{18}$ = $\frac{160}{3}m{s}^{-1}$

$v_{bt}$ = $v_{bg}$ - $v_{tg}$

$\frac{475}{3}$ - $\frac{160}{3}$ = 105 $m{s}^{-1}$