A police van moving on a highway with a speed of `30 km h^(-1)` Fires a bullet at a thief's car speeding away in a same direction with a speed of `192 km h^(-1)`. If the muzzle speed of the buller is `150 m s^(-1)`, with what speed does the bullet hit thief's car? .
.

Options

A. ` 105 ms^(-1)`
B. ` 210 ms^(-1)`
C. ` 315 ms^(-1)`
D. `20 5 ms^(-1)`

Answer

A

Explanation

Speed of thief`s car w.r.t. ground,
` v_(TG)= 30 km h^(-1)`
Speed of polece van w.r.t. ground, ltbr. ` v_(PG)=30 km h^(-1)`
Speed of bullet w.r.t. police van,
` v_(BP) = 150 ms^(-1) = 540 km h^(-1)`
Speed with which the bullet will hit the thief`s car will be
` v_(BT) =v_(BG)+v_(BP)+v_(PG)=v_(GT)`
` = 540 + 30 - 192 ` [ :. v_(GT)=- v_(TG)]`
`= 378 km h^(-1) = 378 xx (1000(/( 3600) ms ^(-1) = 10 ms^(1)`.