Ans
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his velocity is not taken as 9m/s instead as we know that the thief was running at the speed 9m/s and the policeman was moving at 10m/s so if we consider thief at rest then what we did is that subtract 9m/s from its original velocity which results in 0m/s and so we have to do the same for the velocity of policeman i.e. subtract 9m/s which gives us 10-9=1m/s
5 years ago
by
aaditya chaturmohta