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yarga [219]
3 years ago
10

Water flows at speed v in a pipe of radius R. At what speed does the water flow through a constriction in which the radius of th

e pipe is R/3
Physics
1 answer:
Mashcka [7]3 years ago
7 0

Answer:

   v₂ = 9 v

Explanation:

For this exercise in fluid mechanics, let's use the continuity equation

           v₁ A₁ = v₂ A₂

where v is the velocity of the fluid, A the area of ​​the pipe and the subscripts correspond to two places of interest.

The area of ​​a circle is

           A = π R²

let's use the subscript 1 for the starting point and the subscript 2 for the part with the constraint

     

In this case v₁ = v and the area is

            A₁ = π R²

in the second point

           A₂= π (R / 3)²

we substitute in the continuity equation

           v π R² = v₂ π R² / 9

            v = v₂ / 9

           

            v₂ = 9 v

You might be interested in
When waves superimpose and make bigger amplitudes what form of interference is that
eimsori [14]

Answer:

Constructive Interference

Explanation:

Constructive Interference occurs when two waves superimpose and make bigger amplitudes.

In constructive interference, the crests of one wave fall on the crests of second wave and the amplitudes add up. The amplitude of the resultant wave is equal to sum of the amplitude of the individual waves. Similarly, the trough of first wave falls on the trough of other wave and they superimpose to create the trough of the resultant wave.

For Example, In the attachment, two waves A and B superimpose and demonstrate Constructive interference to create the wave C.

7 0
3 years ago
A 3.00N rock is thrown vertically into the air from the ground. At h=15.0m, v=25m/s upward. Use the work-energy theorem to find
butalik [34]

Answer:

so initial speed of the rock is 30.32 m/s

correct answer is b. 30.3 m/s

Explanation:

given data

h = 15.0m

v = 25m/s

weight of the rock m = 3.00N  

solution

we use here work-energy theorem that is express as here

work = change in the kinetic energy    ..............................1

so it can be written as

work = force × distance     ...................2

and

KE is express as

K.E = 0.5 × m × v²  

and it can be written as

F × d = 0.5 × m × (vf)² - (vi)²      ......................3

here

m is mass and vi and vf is initial and final velocity

F = mg = m  (-9.8)  , d = 15 m and v{f} = 25 m/s

so put value in equation 3 we get

m  (-9.8) × 15 = 0.5 × m × (25)² - (vi)²

solve it we get

(vi)² =  919

vi = 30.32 m/s

so initial speed of the rock is 30.32 m/s

5 0
3 years ago
A worker lifts a 20.0-kg bucket of concrete from the ground up to the top of a 25.0-m tall building. The bucket is initially at
yuradex [85]

Answer:

Minimum work = 5060 J

Explanation:

Given:

Mass of the bucket (m) = 20.0 kg

Initial speed of the bucket (u) = 0 m/s

Final speed of the bucket (v) = 4.0 m/s

Displacement of the bucket (h) = 25.0 m

Let 'W' be the work done by the worker in lifting the bucket.

So, we know from work-energy theorem that, work done by a force is equal to the change in the mechanical energy of the system.

Change in mechanical energy is equal to the sum of change in potential energy and kinetic energy. Therefore,

\Delta E=\Delta U+\Delta K\\\\\Delta E= mgh+\frac{1}{2}m(v^2-u^2)

Therefore, the work done by the worker in lifting the bucket is given as:

W=\Delta E\\\\W=mgh+\frac{1}{2}m(v^2-u^2)

Now, plug in the values given and solve for 'W'. This gives,

W=(20\ kg)(9.8\ m/s^2)(25\ m)+\frac{1}{2}(20\ kg)(4^2-0^2)\ m^2/s^2\\\\W=4900\ J +160\ J\\\\W=5060\ J

Therefore, the minimum work that the worker did in lifting the bucket is 5060 J.

7 0
3 years ago
Two identical loudspeakers 2.00 m apart are emitting sound waves into a room where the speed of sound is 340 m/s. Abby is standi
Troyanec [42]

Answer:

The lowest possible frequency of sound is 971.4 Hz.

Explanation:

Given that,

Distance between  loudspeakers = 2.00 m

Height = 5.50 m

Sound speed = 340 m/s

We need to calculate the distance

Using Pythagorean theorem

AC^2=AB^2+BC^2

AC^2=2.00^2+5.50^2

AC=\sqrt{(2.00^2+5.50^2)}

AC=5.85\ m

We need to calculate the path difference

Using formula of path difference

\Delta x=AC-BC

Put the value into the formula

\Delta x=5.85-5.50

\Delta x=0.35\ m

We need to calculate the lowest possible frequency of sound

Using formula of frequency

f=\dfrac{nv}{\Delta x}

Put the value into the formula

f=\dfrac{1\times340}{0.35}

f=971.4\ Hz

Hence, The lowest possible frequency of sound is 971.4 Hz.

8 0
2 years ago
At the end of the Shock Wave roller coaster ride, the 6000-kg train of cars (includes passengers) is allowed from a speed of 20
Angelina_Jolie [31]

Answer:

56250 N

Explanation:

mass, m = 6000 kg

initial speed, u = 20 m/s

final speed, v = 5 m/s

distance, s = 20 m

Use third equation of motion

v^{2}=u^{2}+2as

5 x 5 = 20 x 20 + 2 a x 20

25 = 400 + 40 a

a = - 9.375 m/s^2

Braking force, F = mass x acceleration

F = 6000 x 9.375

F = 56250 N

6 0
3 years ago
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