Ask question

Ask question

All categories

3 years ago

15

A man can swim with a speed of 5m/s in calm water. if this man swims crosses a specific river his speed is 3m/s. if he takes the

minimum time to cross the river find the speed of the flow of water in the river...
plz answer me with all the steps!
I'll give u points ..mark brainliest and follow u

1 answer:

Alex787 [66]3 years ago

4 0

Answer:

The speed of the flow of water in the river is 4 m/s.

Explanation:

Given that,

Speed of man = 5 m/s

If this man swims crosses a specific river his speed is 3 m/s.

If he takes the minimum time to cross the river

Let the speed of flow of water be $v_{r}$

We need to calculate the speed of the flow of water in the river

Using formula for velocity

$v_{rs}^2=v_{r}^2+v_{s}^2$

$v_{r}^2=v_{rs}^2-v_{s}^2$

Where, $v_{s}$ = velocity of swimmer

$v_{sr}$ = relative velocity

$v_{r}$ = velocity of river

Put the value into the formula

$v_{r}^2=5^2-3^2}$

$v_{r}=\sqrt{5^2-3^2}$

$v_{r}=4\ m/s$

Hence, The speed of the flow of water in the river is 4 m/s.

You might be interested in

Were the continents once joined together as a supercontinent? Give 3 pieces of evidence to support Alfred Wegeners Theory of Con

sattari [20]

Yes! Fossils, The outlines of the continents and geological features .

5 0

3 years ago

Read 2 more answers

How do Newton's laws of motion explain why it is important to keep the ice smooth on a hockey rink so that players can

lord [1]

Answer:

I'm not sure..but please refer to your teacher later.

Answer: Based on Newton's First law of motion (where inertia is involved), smooth ice increases the forceused to accelerate the hockey puck.

Explanation;

smooth ice reduces the resistances between the surface of the figure skates and the ice itself.
based on inertia theory ; the heavier the weight, the larger the inertia.. which explains it takes alot of force to move a heavier object than the lighter ones.. it also hard to *stop* the motion of heavier objects than the lighter ones.
now let's look at the design of the player shoe itself, they have a sharp blade at the bottom of the figure stakes.. which takes us to the law of the force.. the smaller the surface area, the more forces acting on it. So, players force (weight, F= mg) acts on the tip of the blade and on the ice
high inertia (run fast) and high force (attack opponent and pass puck) enables them to perform well in playing hockey
Thus if there's no resistance and the inertia of the player is high then they could run and pass the puck quickly

6 0

3 years ago

Read 2 more answers

Briefly explain why arterial injuries are more dangerous than damage to veins

MArishka [77]

Answer:

Injury to a vein increases the risk of forming a blood clot.

Explanation:

hoped this helped

5 0

3 years ago

A charge is divided q1 and (q-q1)what will be the ratio of q/q1 so that force between the two parts placed at a given distance i

Arturiano [62]

Answer:

$q / q_{1} = 2$ , assuming that $q_{1}$ and $(q - q_{1})$ are point charges.

Explanation:

Let $k$ denote the coulomb constant. Let $r$ denote the distance between the two point charges. In this question, neither $k$ and $r$ depend on the value of $q_{1}$ .

By Coulomb's Law, the magnitude of electrostatic force between $q_{1}$ and $(q - q_{1})$ would be:

$\begin{aligned}F &= \frac{k\, q_{1}\, (q - q_{1})}{r^{2}} \\ &= \frac{k}{r^{2}}\, (q\, q_{1} - {q_{1}}^{2})\end{aligned}$ .

Find the first and second derivative of $F$ with respect to $q_{1}$ . (Note that $0 < q_{1} < q$ .)

First derivative:

$\begin{aligned}\frac{d}{d q_{1}}[F] &= \frac{d}{d q_{1}} \left[\frac{k}{r^{2}}\, (q\, q_{1} - {q_{1}}^{2})\right] \\ &= \frac{k}{r^{2}}\, \left[\frac{d}{d q_{1}} [q\, q_{1}] - \frac{d}{d q_{1}}[{q_{1}}^{2}]\right]\\ &= \frac{k}{r^{2}}\, (q - 2\, q_{1})\end{aligned}$ .

Second derivative:

$\begin{aligned}\frac{d^{2}}{{d q_{1}}^{2}}[F] &= \frac{d}{d q_{1}} \left[\frac{k}{r^{2}}\, (q - 2\, q_{1})\right] \\ &= \frac{(-2)\, k}{r^{2}}\end{aligned}$ .

The value of the coulomb constant $k$ is greater than $0$ . Thus, the value of the second derivative of $F$ with respect to $q_{1}$ would be negative for all real $r$ . $F\!$ would be convex over all $q_{1}$ .

By the convexity of $\! F$ with respect to $\! q_{1} \!$ , there would be a unique $q_{1}$ that globally maximizes $F$ . The first derivative of $F\!$ with respect to $q_{1}\!$ should be $0$ for that particular $\! q_{1}$ . In other words:

$\displaystyle \frac{k}{r^{2}}\, (q - 2\, q_{1}) = 0$ <em>.</em>

$2\, q_{1} = q$ .

$q_{1} = q / 2$ .

In other words, the force between the two point charges would be maximized when the charge is evenly split:

$\begin{aligned} \frac{q}{q_{1}} &= \frac{q}{q / 2} = 2\end{aligned}$ .

3 0

3 years ago

Two different liquids are poured into a jar until it is half full. The jar is then sealed shut and shaken. The liquids undergo a

Lilit [14]

Answer:

A closed system.

Explanation:

The three major types of system are: open, closed and isolated. Open system interacts with its surroundings with respect to its particles and energy. A closed system interacts with its surroundings with respect to energy but not its particles. While an isolated system does not interact with its surroundings in any way.

Therefore, after the jar is sealed, it is an example of a closed system. This is because the emitted gas could not escape into the surroundings, but thermal energy was emitted into its surroundings after the chemical reaction has taken place.

7 0

3 years ago