Speed is the average rate at which distance is covered by a moving body
‘s’ = distance(d)/time taken(t) or s = d/t
if Speed is constant then d αt
if Distance is constant then sα1/t
if time is constant then dα s
If certain distance is covered in parts at different speeds,then
1 km/hr = 5/18 m/sec
1 m/sec = 18/5 km/hr
(1) If two objects(Train) are moving in the same direction , then relative
speed of one with respect to other is the difference of the speeds.
(2) If two objects(Train) are moving in the opposite direction , then
relative speed of one with respect to other is the sum of the
Time taken by the train in passing a pole or standing man=
Time taken by the train to cross the bridge=
For Example-A train covers a distance in 50 min, if it runs at a speed of 48kmph on an average. The speed at which the train must run to reduce the time of journey to 40min will be.
Speed = 48mph