question_answer

A police van moving on a highway with a speed of 30 km/h fires a bullet at a thieve's car moving at a speed of 192 km/h. If muzzle speed of bullet is 150 m/s, with what speed does the bullet hit the thieve's car?

A)  195 m/s                              

B)  160 m/s

C)  105 m/s                              

D)  140 m/s

Correct Answer: C

Solution :

\[{{\overrightarrow{v}}_{car,van}}=192-30=162km/h=45m/s\] \[\therefore \]\[{{\overrightarrow{v}}_{bullet,car}}={{\overrightarrow{v}}_{bullet,gun(van)}}+{{\overrightarrow{v}}_{gun(van),car}}\] \[=150-45=105\text{m/s}\]