Question

An object is released at one bank into a river
flowing with speed 5 km/h towards east. Air is
blowing with speed 5 km/h towards north. If width
of river is 200 m, then minimum time taken by
floating object to reach the other bank is (consider
ideal situation)​

Answer 1

Answer:

144sec

Explanation:

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 time to cross the river by the object is 144 sec.

Explanation:

Given that,

Speed of river = 5 km/h

Speed of air = 5 km/h

Width of river = 200 m

So, the object will float in the direction of north east to the flow of the river.

Since, the distance of the river is 0.2 km.

We need to calculate the time to cross the river by the object

Using formula of time

$t= \dfrac{d}{v}$

Where, d = distance

v = velocity

Put the value into the formula

$t=\dfrac{200}{5\times\dfrac{5}{18}}$

$t = 144\ sec$

Hence, The time to cross the river by the object is 144 sec.