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icang [17]
3 years ago
15

Q 17.10: Receiver A detects a sound level of 75 dB at a distance of 25 m from a speaker, which emits sound equally in all direct

ions. Receiver B detects a sound level of 55 dB from the same speaker. How far is receiver B from the speaker
Physics
1 answer:
Ronch [10]3 years ago
4 0

Answer:

250 m

Explanation:

We expect the distance to be more because the sound level has decreased.

Sound level (in decibels) is related to distance by

r_2 = r_1 \times  10^{\frac{|L_1-L_2|}{20}}

where L_1 is the sound level at a distance of r_1 and

L_2 is the sound level at a distance of r_2.

Using the values in the question,

r_{2} = 25\times10^{\frac{|75-55|}{20}} \text{ m}

r_2 = 25\times10^1 \text{ m}= 250 \text{ m}

As a note, when distance increases by 10, the sound level drops by 20 dB, which is what we have in the question.

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A 0.5 m diameter wagon wheel consists of a thin rim having a mass of 7 kg and six spokes, each with a mass of 1.2 kg. 1.2 kg 7 k
Arte-miy333 [17]

Explanation:

It is given that,

Mass of the rim of wheel, m₁ = 7 kg

Mass of one spoke, m₂ = 1.2 kg

Diameter of the wagon, d = 0.5 m

Radius of the wagon, r = 0.25 m

Let I is the the moment of inertia of the wagon wheel for rotation about its axis.

We know that the moment of inertia of the ring is given by :

I_1=m_1r^2

I_1=7\times (0.25)^2=0.437\ kgm^2

The moment of inertia of the rod about one end is given by :

I_2=\dfrac{m_2l^2}{3}

l = r

I_2=\dfrac{m_2r^2}{3}

I_2=\dfrac{1.2\times (0.25)^2}{3}=0.025\ kgm^2

For 6 spokes, I_2=0.025\times 6=0.15\ kgm^2

So, the net moment of inertia of the wagon is :

I=I_1+I_2

I=0.437+0.15=0.587\ kgm^2

So, the moment of inertia of the wagon wheel for rotation about its axis is 0.587\ kgm^2. Hence, this is the required solution.

4 0
3 years ago
The current in a single-loop circuit with one resistance R is 6.3 A. When an additional resistance of 3.4 Ω is inserted in serie
Dmitry [639]

Answer:

10.15Ω

Explanation:

From ohm's law,

V = IR...................... Equation 1

Where V = Voltage, I = current, R = resistance.

Assume the voltage across the resistance = V,

Given: I = 6.3 A

Substitute into equation 1

V = 6.3R.................. Equation 2

When an additional resistance of 3.4 Ω is inserted in series with R,

The voltage remain the same, but the current changes

Total Resistance(Rt) = (R+3.4)Ω, I' = 4.72 A

Also from ohm' law,

V = I'Rt............... Equation 3

Substitute the value of I'  and Rt into equation 3

V = 4.72(R+3.4)............... Equation 5.

Divide equation 2 by equation 5

V/V = 6.3R/4.72(R+3.4)

1 = 1.335R/(R+3.4)

1 = 1.335R/(R+3.4)

R+3.4 = 1.335R

3.4 = 1.335R-R

3.4 = 0.335R

R = 3.4/0.335

R = 10.15Ω

6 0
2 years ago
Read 2 more answers
Which two statements are true about a system?
weqwewe [10]

Answer:The correct options are:

1. A system is a group of objects analyzed as one unit.

2. Energy that moves across system boundaries is conserved.

Explanation:

A system is defined as group of interrelated or interacting items existing as a single unit or a whole to achieve a specific objective.Energy lost by the system is equal to the energy gained by the surroundings.

Two statements are true about a system:

  • A system is a group of objects analyzed as one unit.
  • Energy that moves across system boundaries is conserved.
3 0
3 years ago
Read 2 more answers
Select Light for the type of wave, adjust the wavelength so that the light is red, and increase the amplitude of the light to th
Sergeu [11.5K]

Answer:

here as we increase the distance the intensity will decrease and hence the amplitude of the electric field will decrease and vice-versa

Explanation:

As wee know that the amplitude of the wave will decide the energy of the wave

Here we know that energy density of electromagnetic wave is given as

u = \frac{1}{2}\epsilon_0E_0^2

now we have

\frac{I}{c} = \frac{1}{2}\epsilon_0 E_0^2

so here we can say that intensity of the wave at the given distance from the source is given by formula

I = \frac{P}{4\pi r^2}

so here as we increase the distance the intensity will decrease and hence the amplitude of the electric field will decrease and vice-versa.

5 0
3 years ago
What is a benefit of increased physical fitness
8_murik_8 [283]
The benefit's of increased physical fitness is better health, more pleasing appearance to some, stronger muscles and the reduction of fat.
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3 years ago
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