A vector problem

I couldn't solve this problem.Can anyone help??

A man can cross a 100 meter width river in 4 minutes straightly when there is no current in the river.But when the current is available he can cross it in 5 minutes.What is the speed of the current?

#Vectors #Speed #Dynamics

Easy Math Editor

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Comments

His velocity is 100 meters in 4 minutes, or 25 meters per minute.

It states that with a river current, he takes 5 minutes to cross. This means he traveled a total of 125 meters relative to the current.

Now suppose that instead of the river having a current and the man traveling in a straight line, the river is still stationary and the man is traveling in a slanted line. We have that the slanted line is 125 meters, the distance from coast to coast is 100 meters; therefore, he traveled $\sqrt{125^2-100^2}=75$ meters away from the point where he would have landed if he had traveled in a line perpendicular to the river. This 75 meters accounts for the current: the current travels 75 meters in 5 seconds, or $\boxed{25\text{ meters per second}}$ .

Daniel Liu - 7 years, 3 months ago

The last computation is the most awful one, no? "75 minutes in 5 minutes, or 15 meters per minute" (or 0.25 meters per second).

Ivan Koswara - 7 years, 3 months ago

75 meters in five minutes so its 0.25 meters per second.........??

Vishnu Suresh - 7 years, 3 months ago

Thanks

Irtesam Mahmud Khan - 7 years, 3 months ago

Its 15m/s.

jinay patel - 7 years, 3 months ago

Math	Appears as
Remember to wrap math in `\(` ... `\)` or `\[` ... `\]` to ensure proper formatting.
`2 \times 3`	$2 \times 3$
`2^{34}`	$2^{34}$
`a_{i-1}`	$a_{i-1}$
`\frac{2}{3}`	$\frac{2}{3}$
`\sqrt{2}`	$\sqrt{2}$
`\sum_{i=1}^3`	$\sum_{i=1}^3$
`\sin \theta`	$\sin \theta$
`\boxed{123}`	$\boxed{123}$