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photoshop1234 [79]
3 years ago
15

The intensity of a certain siren is 0.060 W/m^2 from a distance of 25 meters. What is the intensity of this siren at a distance

of 50 meters?
Physics
1 answer:
Nady [450]3 years ago
7 0
<h2>The intensity of siren is 0.015 W m⁻²</h2>

Explanation:

The intensity of sound is inversely proportional to the square of distance between source and the observer .

Thus Intensity at a distance 25 m  is I₁ ∝ \frac{1}{r_1^2}                               I

Similarly the intensity at a distance 50 m is I₂ ∝ \frac{1}{r_2^2}               II

Dividing II by I , we have

\frac{I_2}{I_1} = \frac{r_1^2}{r_2^2} = \frac{25^2}{50^2} = \frac{1}{4}

Thus I₂ = \frac{1}{4} x 0.06 =  0.015 W m⁻²

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A 66-kg diver jumps off a 9.7-m tower. (a) Find the diver's velocity when he hits the water. (b) The diver comes to a stop 2.0 m
Mariana [72]

Answer:

(a)  13.795 m/s.

(b) -3140.28 N.

Explanation:

(a) Using newton's  equation of motion,

v² = u² + 2gs.......................... Equation 1

Where v = final velocity, u = initial velocity, s = height of the tower, g = acceleration due to gravity.

Given: s = 9.7 m, u = 0 m/s ( jump from a height), g = 9.81 m/s².

Substitute into equation 1

v² = 0² + 2×9.81×9.7

v² = 190.314

v = √(190.314)

v = 13.795 m/s.

Hence the velocity of the driver when he hits the water = 13.795 m/s.

(b)

F = ma.................... Equation 2

Where F = force exerted on the diver, m = mass of the diver, a = acceleration of the diver below the water surface.

Also using

v² = u² + 2as ............ Equation 3

Note: At the point when the diver enters the water, u = 13.795 m/s, and at the point when the diver comes to a complete stop, v = 0 m/s

Given: s = 2.0 m, u = 13.795 m/s, v = 0 m/s

Substitute into equation 3

0² = 13.795²+2(2a)

0 = 190.30203 + 4a

-4a = 190.30203

a = 190.30203/-4

a = -47.58 m/s²

Also given: m = 66 kg,

Substitute into equation 3

F = (-47.58)(66)

F = -3140.28

Note: The Force is negative because it act against the motion of the diver.

Hence the net force exerted on the diver while in the water = -3140.28 N.

7 0
3 years ago
#1 Not sure where to start. This is for AP Physics!
yaroslaw [1]

First,

\rho=\dfrac mV

where \rho is density, m is mass, and V is volume. We can compute the volume of the roll:

2.7\,\dfrac{\mathrm g}{\mathrm{cm}^3}=\dfrac{1275\,\mathrm g}V

\implies V\approx472.22\,\mathrm{cm}^3\approx4.72\,\mathrm m^3

When the roll is unfurled, the aluminum will be a rectangular box (a very thin one), so its volume will be the product of the given area and its thickness x. Note that we're assuming the given area is not the actual total surface area of the aluminum box, but just the area of the largest face (i.e. the area of one side of the unrolled sheet of aluminum).

So we have

V=Ax

where A is the given area, so

4.72\,\mathrm m^3=\left(18.5\,\mathrm m^2\right)x

\implies x\approx0.255\,\mathrm m=255\,\mathrm{mm}

If we're taking significant digits into account, the volume we found would have been V=470\,\mathrm m^3, in turn making the thickness x=250\,\mathrm{mm}.

8 0
3 years ago
What is the easiest way of writing a chemical<br>reaction?​
viktelen [127]

Answer:

Writing reactants on the left, and the products are written on the right

Explanation:

5 0
2 years ago
A certain water wave has a wavelength of 25 m and a frequency of 4.0 Hz. What is its velocity?
babymother [125]
Wave speed = frequency * wavelength
Wave speed = 4 * 25
Wave speed = 100 m/s
8 0
3 years ago
None of these make sense someone help
vfiekz [6]

I would say B because the rest of them are false.

Because Saturn is made of gas

Saturn is smaller than Jupiter

And it takes 29 years for Saturn to orbit the sun

Hope This Helps!     Have A Nice Day!!

6 0
3 years ago
Read 2 more answers
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