Question

A train of length 700m travelling at 90Km/h overtake a motorcyclist in 70 sec. After half an hr train crosses a cyclist in 20 sec.After how much more time will motorcyclist & cyclist meet?

Answer 1

Answer:

12 Mins

Step-by-step explanation:

A train of length 700m travelling at 90Km/h overtake a motorcyclist in 70 sec

Distance Traveled by Train in 70 sec =  (70/3600)* 90  = 7/4 km = 1750 m

Distance covered by motorcyclist = 1750 m - 700 m  = 1050 m

Speed of Motorcyclist = 1050/70  =  15 m/s

in 1/2 hr train covered distance =  (1/2)90 =  45 km = 45000 m

Distance covered by bike in 1/2 hr (1800 sec)  = 15 * 1800 = 27000 m

Distance  between Motorcyclist & cyclist = 45000 - 27000 = 18000 m

Distance Traveled by Train in 20 sec =  (20/3600)* 90  = 1/2 km = 500 m

Distance covered by Cyclist = 500 m - 700 m  =  -200 m

=> Cyclist is coming in opposite direction to Train

Speed of cyclist =200/20  =  10 m/s

As Motorcyclist & cyclist are in opposite direction

so their net speed = (15 + 10) = 25 m/s

Distance to be covered = 18000 m

Time taken = 18000/25 = 720 sec = 12 mins