Question

A police jeep is chasing a thief with velocity of $45\text{km/h}$. The thief is in another jeep moving with velocity $153\text{km/h}$. Police fires a bullet with muzzle velocity of $180\text{m/s}$ The velocity of the bullet with respect to the jeep of the thief is:

• A. $150\text{m/s}$
• B. $27\text{m/s}$
• C. $450\text{m/s}$
• D. $250\text{m/s}$

Answer 1

The correct option is A $150\text{m/s}$

Effective speed of the bullet
= speed of bullet + speed of police jeep
$=180\text{m/s}+45\text{km/h}=(180+12.5)\text{m/s}=192.5\text{m/s}$
Speed of thief's jeep $=153\text{km/h}=42.5\text{m/s}$
Velocity of bullet w.r.t thief's car $192.5-42.5=150\text{m/s}$