Q118 / 160 · JIPMER 2005 · Physics
A police jeep is chasing with velocity of $45 \mathrm{~km} / \mathrm{h}$. A thief in another jeep moving with velocity $153 \mathrm{~km} / \mathrm{h}$. Police fires a bullet with muzzle velocity of $180 \mathrm{~m} / \mathrm{s}$. The velocity it will strike the car of the thief is
- Correct answerA$150 \mathrm{~m} / \mathrm{s}$
- B$27 \mathrm{~m} / \mathrm{s}$
- C$450 \mathrm{~m} / \mathrm{s}$
- D$250 \mathrm{~m} / \mathrm{s}$
Solution
Effective speed of bullet is \(=\) Speed of bullet + Speed of police jeep
\(\begin{aligned}
& =18 \mathrm{om} / \mathrm{s}+45 \mathrm{~km} / \mathrm{hr} \\
& =180+45 \times \frac{5}{18} \mathrm{~m} / \mathrm{s} \\
& =192.5 \mathrm{~m} / \mathrm{s}
\end{aligned}\)
Speed of theifs jeep \(=153 \mathrm{~km} / \mathrm{hr}=42.5 \mathrm{~m} / \mathrm{s}\)
Velocity of bullet with respect to theif's jeep \(=192.5-42.5 \mathrm{~m} / \mathrm{s}\)
\(=150 \mathrm{~m} / \mathrm{s}\)
Hence, the correct answer is option: 'A'.