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mylen [45]
3 years ago
12

a man can row about 4kmperhr in a still water.he rows the boat 2km up the stream and 2km back to his starting point in 2hr.how f

ast is the stream flowing. ​
Physics
1 answer:
Nat2105 [25]3 years ago
7 0

<u>Answer</u>:

The stream flowing  at a speed of 2.828 \mathrm{km} / \mathrm{hr}

<u>Explanation</u>:

Given:  

Distance = 2km (both in upstream and downstream)  

The speed in still water be x km/hr.  

The speed in upstream = 4-x  

Speed in downstream = 4+x  

Solution:

We know that, Speed = distance/time  

So, Time = distance/speed

Therefore,  

2=\left(\frac{2}{4-x}\right)+\left(\frac{2}{4+x}\right)

2=\frac{2(4+x)+2(4-x)}{(4-x)(4+x)}

2(4-x)(4+x)=2(4+x)+2(4-x)

2(4-x)(4+x)=2(4+x+4-x)

By cancelling 2 on both sides,

16-x^{2}=8

x^{2}=16-8=8

x=\sqrt{8}

x=2.828 \mathrm{km} / \mathrm{hr}

Result:

Thus the speed of the stream is 2.828 \mathrm{km} / \mathrm{hr}

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