The term times and distance area related to the speed of moving objects
Speed — We define the speed of an object as the distance covered by it in a unit time interval.
Speed =(Distance travelled)/(time taken)
⇒ Distance travelled = Speed × time
⇒ Time = Distance/Speed
Unit of measurement
If distance is measured in kilometer, we measure time in hours and speed is written as km/hr.
If distance is measured in meter, then time is taken in second and speed written as m/s
Conversion of unit
1 km/hr = (1000 mtr)/(60×60 seconds)=5/18 m/s
1 m/s =18/5 km/hr
Ex. – A train having length 500 m passes a pole in 30 second. Find the speed of a train (in km/hr)
⇒Speed=Distance/time=500/30 m/s
=500/30×18/5 km/hr
= 60 km/hr
Some useful short cut methods
