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A thief is spotted by the police at a distance of 300m. On seeing the police, the thief takes off on a motor cycle at a speed of 15 m/s. If the thief is caught in 1 min 40 seconds, find the speed of the police.1. 12 m/s2. 15 m/s3. 18 m/s4. 21 m/s5. 24 m/s |
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Answer» Correct Answer - Option 3 : 18 m/s Given: Distance at which the thief is spotted = 300 m Speed of thief = 15 m/s Time taken by the police to catch the thief = 1 min 40 seconds = 100 s Concept used: Time taken for the police to catch the thief = distance/(relative speed) Relative speed = SP – ST, when both are going in same direction. Calculation: Time taken for the police to catch the thief = 300/(SP – 15) = 100 s ⇒ 3 = SP – 15 ⇒ SP = 18 m/s ∴ The required speed is 18 m/s. |
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