Question

An object is released at one bank into a river flowing with speed 5km / h towards East. Air is blowing with speed 5km / h towards north. if width of river is 200 m then time taken by the floating object to reach the other bank is
1)144 min
2)3.4 seconds
3)144 second
4)14.4 second​

Answer 1

Answer:

144sec

Explanation:

Tricky question.

The minimum time is the minimum distance travelled. Here it is travelling nortth.

Hence, t = d / v = 0.2 km/( 5 km/hr) = 0.04 hr = 0.04*3600 = 144 secs.

Answer 2

Answer:

The speed of the river is 5 km/hr towards east when the object is released from the bank and the wind speed is 5 km/hr towards north then the object will float in the direction of north east to the flow of the river.

Since, the distance of the river is 200 m or 0.2 km then the time required to cross the river by the object will be.

Time t = d / v = 0.2/ 5 = 0.04 hr which in seconds will be 0.04*3600 = 144 secs.