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3 years ago

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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. Nine times higher. B. Nine times lower. C. Three times higher. D. Three times lower.

1 answer:

Eva8 [605]3 years ago

4 0

The intensity of the sound will be B. Nine times lower

Explanation:

The intensity of a sound follows an inverse square law, which means that it is inversely proportional to the square of the distance from the source:

$I\propto \frac{1}{r^2}$

where

I is the intensity

r is the distance from the source

In this problem, the siund has an intensity of I when the receiver is placed at a distance r from the source.

Later, the receiver is placed three times farther away, so the new distance is

r' = 3r

Therefore, the new intensity of the sound will be:

$I'\propto \frac{1}{r'^2}=\frac{1}{(3r)^2}= \frac{1}{9} (\frac{1}{r^2})= \frac{1}{9}I$

Therefore, the intensity of the sound received will be nine times lower.

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A 16.2 kg person climbs up a uniform ladder with negligible mass. The upper end of the ladder rests on a frictionless wall. The

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To solve this problem we will apply the concepts related to the balance of forces. We will decompose the forces in the vertical and horizontal sense, and at the same time, we will perform summation of torques to eliminate some variables and obtain a system of equations that allow us to obtain the angle.

The forces in the vertical direction would be,

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$f-N_w = 0$

$N_w = f$

The forces in the horizontal direction would be,

$\sum F_y = 0$

$N_f -W =0$

$N_f = W$

The sum of Torques at equilibrium,

$\sum \tau = 0$

$Wdcos\theta - N_wLsin\theta = 0$

$WdCos\theta = fLSin\theta$

$f = \frac{Wd}{Ltan\theta}$

The maximum friction force would be equivalent to the coefficient of friction by the person, but at the same time to the expression previously found, therefore

$f_{max} = \mu W=\frac{Wd}{Ltan\theta}$

$\theta = tan^{-1} (\frac{d}{\mu L})$

Replacing,

$\theta = tan^{-1} (\frac{0.9}{0.42*2})$

$\theta = 46.975\°$

Therefore the minimum angle that the person can reach is 46.9°

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3 years ago

Which occurrence would lead you to conclude that lights are connected in a

skelet666 [1.2K]

Answer:B When one bulb burns out, all the others lights stay lit.

Explanation:

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The owner of a company that manufactures drinking cups decides it would be impressive to build an inground swimming pool that is

garri49 [273]

Answer:

The depth is 5.15 m.

Explanation:

Lets take the depth of the pool = h m

The atmospheric pressure ,P = 101235 N/m²

The area of the top = A m²

The area of the bottom = a m²

Given that A= 1.5 a

The force on the top of the pool = P A

The total pressure on the bottom = P + ρ g h

ρ =Density of the water = 1000 kg/m³

The total pressure at the bottom of the pool = (P + ρ g h) a

The bottom and the top force is same

(P + ρ g h) a = P A

P a +ρ g h a = P A

ρ g h a = P A - P a

$h=\dfrac{P ( A-a)}{\rho g a}$

$h=\dfrac{P ( 1.5 a-a)}{\rho g a}$

$h=\dfrac{P ( 1.5- 1)}{\rho g}$

$h=\dfrac{101235 ( 1.5- 1)}{1000\times 9.81}\ m$

h=5.15 m

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3 years ago

When the current in a toroidal solenoid is changing at a rate of 0.0240 A/s , the magnitude of the induced emf is 12.4 mV . When

Gemiola [76]

Answer:

The number of turns in the solenoid is 230.

Explanation:

Given that,

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The induced emf through the solenoid is given by :

$\epsilon=L\dfrac{dI}{dt}$

or

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From equation (1) and (2) we get :

$\dfrac{\epsilon}{(di/dt)}=\dfrac{N\phi}{I}$

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$N=\dfrac{\epsilon I}{\phi (dI/dt)}$

$N=\dfrac{12.4\times 10^{-3}\times 1.5}{0.00338 \times 0.024}$

N = 229.28 turns

or

N = 230 turns

So, the number of turns in the solenoid is 230. Hence, this is the required solution.

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A box has a mass of 35kg.he pulls the rope horizontally with a force of 175 N. Find the horizontal acceleration of the box as it

Cloud [144]

Answer:

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Explanation:

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Using the equation for acceleration, we take the force and divide it by mass.

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*Note: This is rounded to the nearest hundredth, the full answer is: 3.42857143

**Note: In case you're confused, this is meters per second squared.

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