Train 100m and person on bike traveling towards each other and find time with the given speed

Question

A train 100 m in length travels at 54 km/hr. How much time will it take pass a man who is riding a bike at 36 km/hr in the opposite direction?

A train 100 m in length travels at 54 km/hr. How much time will it take pass a man who is riding a bike at 36 km/hr in the opposite direction?

Answer 1

Hi Liz,

 

The trick is to notice that since the train is going 54 km/hr and the bike is going straight towards it at 36 km/hr, the total speed is 54 + 36 = 90 km/hr. Then convert to m/hr to get:

 

90 km/hr x 1000 m/km = 90,000 m/hr

 

Now you want to see how long it takes to travel 100 m, so use the distance formula, d = rate x time to get:

 

100 = 90,000 x time --> time = 100 / 90,000 = 1/900 hours

 

Converting this to seconds, you get:

 

1/900 hr x 60 min/hr x 60 sec/min = 4 seconds

 

Hope that helps!

 

Daniel