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luda_lava [24]
3 years ago
15

A surface receiving sound is moved from its original position to a position three times farther away from the source of the soun

d. the intensity of the received sound thus becomes
a. three times as high.
b. three times as low.
c. nine times as high.
d. nine times as low.
Physics
2 answers:
murzikaleks [220]3 years ago
5 0
As long as all the waves stay in the same medium, the intensity of
any waves ... electromagnetic or mechanical ... decrease in proportion
to the square of the distance.

If the distance increases to 3 x the original distance, then the intensity
changes to  1/3² or 1/9 of the original intensity.

I suppose choice-'d' is the correct one, but I have to tell you that
the phrase "nine times as low" is mathematically meaningless,
and it really grinds my gears.
shepuryov [24]3 years ago
5 0

Correct answer choice is :


D) Nine times as low.


Explanation:


Sound intensity level also identified as acoustic intensity is described as the energy taken by sound waves per unit area in a path perpendicular to that area. The SI unit of intensity, which involves sound intensity, is the watt per square meter (W/m2). The loudness of a sound describes the intensity of any given sound to the intensity at the start of sound. It is marked in decibels (dB).

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A tennis ball with a velocity of +10.0 m/s to the right is thrown perpendicularly at a wall. After striking the wall, the ball r
netineya [11]

Answer:

-1500 m/s2

Explanation:

So the ball velocity changes from 10m/s into the wall to -8m/s in a totally opposite direction within a time span of 0.012s. Then we can calculate the average acceleration of the ball as the change in velocity over a unit of time.

a = \frac{\Delta v}{\Delta t} = \frac{-8 - 10}{0.012} = \frac{-18}{0.012} = -1500 m/s^2

6 0
3 years ago
# A cheetah can start from rest and attain the velocity 72km/h in 2 seconds. Calculate the acceleration of cheetah
yan [13]

Answer:

<h2>10 \: m/s ^2</h2><h2 />

Explanation:

Solution,

When a certain object comes in motion from rest, in the case, initial velocity = 0 m/s

Initial velocity ( u ) = 0 m/s

Final velocity ( v ) = 72 km/h ( Given)

We have to convert 72 km /h in m/s

72 \: km \: per \: hour

= 72 \times  \frac{1000}{60  \times 60}

= 20 m/s

Final velocity ( v ) = 20 m/s

Time taken ( t ) = 2 seconds

Acceleration (a) = ?

Now,

we have,

a =  \frac{v - u}{t}

a =  \frac{20 - 0}{2}

a =  \frac{20}{2}

a = 10 m/s ^2

Hope this helps...

Good luck on your assignment..

7 0
3 years ago
A 44-turn rectangular coil with length ℓ = 17.0 cm and width w = 8.10 cm is in a region with its axis initially aligned to a hor
Mumz [18]

Answer:

The maximum induced emf in the rotating coil  = 29.66V

The induced emf in the rotating coil when (t = 1.00 s) = 26.66V

The maximum rate of change of the magnetic flux through the rotating coil = 0.674Wb/s

Explanation:

Lets state the parameters we are being given right from the question:

Number of rectangular coil, (N) = 44

Length of Coil, l =17cm in meters we have; (l) = 17 × 10⁻² m

Width of Coil, w =8.10cm in meters we have; (w) = 8.10 × 10⁻² m

Magnitude of Uniform Magnetic Field (B) = 767mT= 765 × 10⁻³ T

Angular Speed of Coil, (ω) = 64 rad/s

(a)

To calculate the induced emf in the rotating cell,we can use the formula:

emf = NBAωsin(ωt)

For maximum induced emf, the value of sin(ωt) will be 1

emf_max = NBAω ; if (A = l × w) , we have:

emf_max  = NB(l × w)ω

subsitituting the parameters into the above equation; we have:

emf_max  = 44 × 765 × 10⁻³ ( 17 × 10⁻² × 8.10 × 10⁻² ) × 64

= 29.66V

(b)

At t = 1s, the induced emf is calculated as:

emf = NBAωsin(ωt)

substituting the parameters into the equation, we have:

emf =   44 × 765 × 10⁻³ ( 17 × 10⁻² × 8.10 × 10⁻² ) × 64 × sin (64 × 1)

=26.66V

(c)

To calculate the maximum rate of change of the magnetic flux through the rotating coil; we need to reflect on the equation for the maximum induced emf in terms of magnetic flux.

i.e emf_max = N\frac{d∅}{dt}

since emf_max = 29.66 and N = 44; we have:

29.66 =  44\frac{d∅}{dt}

\frac{d∅}{dt} = \frac{29.66}{44}

= 0.674 Wb/s

5 0
3 years ago
Two spectators at a soccer game see, and a moment later hear, the ball being kicked on the playing field. The time delay for the
WINSTONCH [101]

Answer:

a)188.65m

b)154.35m

c)243.7m

Explanation:

Given data:

t_A=0.55s

t_B=0.45s

(a) The distance from the kicker to each of the 2 spectators is given by:

d_A=v \times t_A

where,

v= speed of sound

t_A=time taken for the sound waves to reach the ears

d_A=343\times 0.55=188.65m

(b)d_B=v \times t_B

where,

v= speed of sound

t_B=time taken for the sound waves to reach the ears

d_B=343\times 0.45=154.35m

(c)As the angle b/w slight lines  from the two spectators to the player is right angle,

hypotenuse=the distance b/w 2 spectators

and, the slight lines are the other 2 lines

D^2=d_A^2+d_B^2\\D=\sqrt{188.65^2+154.35^2} \\D= 243.7m

5 0
3 years ago
Describe the relationship between motion<br> and a reference point.
steposvetlana [31]

Answer:

An object is in motion when its distance from another object is changing. ... A reference point is a place or object used for comparison to determine if something is in motion. An object is in motion if it changes position relative to a reference point. You assume that the reference point is stationary, or not moving.

Explanation:

4 0
3 years ago
Read 2 more answers
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