Speed = Distance / Time
1 kmph = 5/18 m/sec; 1 m/sec = 18/5 kmph
If the distance covered is constant then the average speed is the Harmonic Mean of the values (s1, s2, s3….sn)
If the time taken is constant then the average speed is the Arithmetic Mean of the values (s1, s2, s3….sn)
EduRev's Tip: Given that the distance between two points is constant, then
⇒ If the speeds are in Arithmetic Progression, then the times taken are in Harmonic Progression
⇒ If the speeds are in Harmonic Progression, then the times taken are in Arithmetic Progression
For Trains, time taken =
For Boats,
SpeedUpstream = SpeedBoat – SpeedRiver
SpeedDownstream = SpeedBoat + SpeedRiver
SpeedBoat = (SpeedDownstream + SpeedUpstream) / 2
SpeedRiver = (SpeedDownstream – SpeedUpstream) / 2
For Escalators, The difference between escalator problems and boat problems is that escalator can go either up or down.
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