Question

A 140 meter long train passes a pole in 12 seconds. The speed of the train in km per hour is

Answer 1

The speed of train in km/h is.l------ 140÷12×18÷5 = 27 km/h

Answer 2

The speed of the train in km/hr is 42 km/hr

• Speed is defined as rate of change of distance traveled.
• It's formula is

             $speed = \frac{distance traveled}{time}$

• The S.I unit of speed is m/s.

PROBLEM:

• Given,

            Distance traveled = 140 m

            Time                       = 12 s

            Speed = 140/12

                        = 35/3 m/s

• To convert m/s into km/hr, we need to multiply with 18/5

            Speed = $(\frac{35}{3} )(\frac{18}{5} )$ km/hr

                         = 630/15 km/hr

                         = 42 km/hr