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3 years ago

13

a man can swim in still water with speed of 2kmhr-1 wants to cross a river 200m wide flowing with 1kmhr-1 . Calculate the time t

aken by the man to cross river in shortest time.

1 answer:

tangare [24]3 years ago

3 0

Answer:

d savage

Explanation:

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When the body requires an increased blood flow rate in a particular organ or muscle, it can accomplish this by increasing the di

horsena [70]

Answer: The percentage increase in diameter is 19%

Explanation:

<em>Using Poiseuille's law which states that Flow rate , Q = ΔPπr⁴/8ηl</em>

<em>where ΔP is pressure difference, π is a constant, r is the radius which is half of the diameter, η is viscosity of blood, l is length of blood vessel</em>

Let Q₁ be the intitial flow rate, Q₂ the final flow rate,r₁ and r₂ the initial and final radius.

Note: r = d/2, therefore, r₁⁴ = d₁⁴/16 r₂⁴ = d₂⁴/16

Also, Q₂ = 2Q₁, since the flow rate is doubled

Since all factors except diameter is constant, d₂⁴/16 = 2d₁⁴/16

d₂⁴/16 = d₁⁴/8

multiply both sides of the equation by 16

d₂⁴ = 2d₁⁴

taking the fourth root of both sides

d₂ = 1.19*d₁

d₂ - d₁ = 1.19d₁ - d₁

d₂ - d₁ = d₁(1.19 - 1)

d₂ - d₁ = 0.19d₁

d₂ - d₁/d₁ = (0.19d₁/d₁)*100%

(d₂ - d₁/d₁)*100% = 19%

Therefore, the percentage increase in diameter is 19%

3 0

4 years ago

Evgen [1.6K]

Answer:

Circuit one will have more current than circuit two

Explanation:

I am assuming that you have to see which circuit has the greater current in this case. Well, this is the perfect example of Ohm's Law, which states the following -

V = IR,

where V = voltage / potential difference, I = current, and R = resistance

If one circuit has twice the voltage and half the resistance of the second circuit, as voltage is directly proportional to the resistance -

2V = I( 1 / 2R ),

4V = IR,

I = 4V / R

Whereas in the second circuit -

V = IR,

I = V / R

As you can note, voltage is directly proportional to the current ( I ) as well as the resistance. The only difference between the two formulas I = 4V / R, and I = V / R is the difference in the voltage. With the voltage being 4 times greater in the first circuit, and current is 4 times greater in the first circuit as well.

<u><em>Hence, circuit one will have more current than circuit two</em></u>

5 0

4 years ago

Read 2 more answers

What are possible units for impulse? Check all that apply. kg • m kg • N • s N • m

Vlada [557]

We know that impulse is simply the product of Force and time:

Impulse = Force * time

Since Force has a unit of Newton or kg m/s^2 and time is in seconds, therefore impulse can have units as:

N s

or

<span>kg m/s</span>

4 0

3 years ago

A ball, initially at rest, reaches a speed of 20 m/s at the bottom of the apparatus. If it takes the ball 10 seconds to reach th

MariettaO [177]

Answer:

2 m/s²

Explanation:

Given:

v₀ = 0 m/s

v = 20 m/s

t = 10 s

Find: a

a = (v − v₀) / t

a = (20 m/s − 0 m/s) / 10 s

a = 2 m/s²

3 0

3 years ago

N2 + 3H2 mc033-1.jpg 2NH3

Svetradugi [14.3K]

N2+3H2->2NH3

When 3 moles of H2 react, they produce 2 moles of NH3

3 moles of H2 have a mass of 2.02 g

2 moles of NH2 have a mass of 17.0 g

So when 2.02 g H2 react, they produce 17.0 g NH3

If 26.3g H2 react with a yield of 100%, we expect…

2.02g H2_____17.0gNH3

26.3g H2_____x=221gNH3

So now let’s calculate the percentage:

221gNH3_________100%

79.0gNH3_________x=79.0*100/221=35.7%

3 0

3 years ago