Question

A boat takes 3.9 hours to travel 25 km down a river, then 6.9 hours to return. You may want to review (Pages 876 - 878) .

Part A Determine the speed of the water in the river.

Answer 1

Suppose the speed of water in the river is = Vw

Speed of boat = Vb

when boat is moving downward or with the stream, Speed will be = Vb + Vw

when boat is moving upward or against the stream, Speed will be = Vb - Vw

Now given that

distance = 25 km

Speed = distacne/time

So,

In downward motion

Vb + Vw = 25 km/3.9 hr = 1.781 m/sec

In upward motion

Vb - Vw = 25 km/6.9 hr = 1.006 m/sec

Add both equation

2*Vb = 1.781 + 1.006

Vb = 2.787/2 = 1.3935 m/sec = 5.02 km/hr

Vw = 1.781 - 1.3935 = 0.3875 m/sec = 1.395 km/hr

Please Upvote. And Check the units before entering final answer.