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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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The acceleration of a rocket engine is given here, and after 50 seconds of flight, the engine fails, and we must determine the altitude of the rocket at the time the engine fails.  Because the rocket starts from rest, the time taken is 50 seconds, the initial velocity is zero, and the acceleration is 22.9 meters per second square. So we use the kinamatics equation s equal to v. I t plus half 8 square. There is no acceleration at the start. 22.9 and t is 50 seconds, so displacement 2.86 times 10 to the power 4 is met. This is the rocket's displacement in 50 seconds, so this is the rocket's altitude when the engine fails.

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Hence, There is no acceleration at the start. 22. This is the rocket's displacement in 50 seconds, so this is the rocket's altitude when the engine fails.

To know more about Accelerate refer to:

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