Can someone please help me

When an underwater sound source emits waves of frequency 30 kHz in all directions, the intensity of the waves (in Watts/m2) vary with distance r from the source by the relation 1/r²

As the intensity mechanical sound wave is inversely proportional to the square of the distance from the source, therefore the correct option is B.

Wavelength can be understood in terms of the distance between any two similar successive points across any wave for example wavelength can be calculated by measuring the distance between any two successive crests.

It is the total length of the wave for which it completes one cycle.

The intensity of a mechanical wave is inversely proportional to the square of the distance from the source.

An underwater sound source emits waves of frequency of 30 kHz in all directions, the intensity of the waves (in Watts/m2) varies with distance r from the source by the relation 1/r², therefore the correct option is B.

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Newton's First Law states that an object will remain at rest or in uniform motion in a straight line unless acted upon by an external force.

THIS LAW IS TRUE AS IT ALSO HAVE A REAL LIFE EXAMPLE.

Examples of Newton's 1st Law : If you slide a hockey puck on ice, eventually it will stop, because of friction on the ice. It will also stop if it hits something, like a player's stick or a goalpost.

Recall that

v² - u² = 2 a ∆x

where u and v are initial and final velocities, respectively; a is acceleration; and ∆x is the distance traveled (because the skater moves in only one direction).

So we have

(5.8 m/s)² - (8.8 m/s)² = 2 a (6.0 m)

a = ((5.8 m/s)² - (8.8 m/s)²) / (12 m)

a = -3.65 m/s²

Answer:

Water because the salt will just make it colder and the sugar won't do anything

Answer:

Sound travels slower than light

Explanation:

Sound travels at around 1/3 km per second, while light travels around 300,000 km per second.

Also, this is the reason you see the lightning before you hear the thunder.

I hope this helped.

Answer:

Sound travels slower than light

Explanation:

Bc light is faster than sound

Answer:

Can become non-renewable but it depends on the object

Explanation:

Answer:

Renewable resources are so abundant or are replaced so rapidly that, for all practical purposes, they can't run out. Fossil fuels are the most commonly used non-renewable resources

Explanation:

Hope this helps (:

Answer:

22.3 kg•m/s

Explanation:

Apex;)

Answer:

Mass was added to the water particles, resulting in deposition.

Explanation:

Answer:  The energy was removed from the water particles resulting in condensation

Explanation Think about when you leave a cup of ice of and after a while you see water droplets thats what happened to the grass in the morning and thats called condensation.

Answer:

Sand is a form of physical change because it shows how one object is being worn out (broken down) into another object by nature.

Explanation:

We know, force is given by :

[tex]F=\dfrac{kq_1q_2}{r^2}[/tex]

Here, k in a constant.

[tex]Net \ Force = F_1+F_2\\\\Net \ Force = k(\dfrac{Qq_1}{r_1^2}+\dfrac{Qq_2}{r_2^2})\\\\Net \ Force = k( \dfrac{-3}{50}+\dfrac{2}{50})\\\\Net \ Force = 9\times 10^9\times \dfrac{-1}{50}\ N\\\\Net\ Force = -1.8\times 10^8\ N[/tex]

Hence, this is the required solution.

Answer:

a. the amount of work done on a system is dependent of pathway

Explanation:

The first law of thermodynamics states that the change in internal energy of a system equals the net heat transfer into the system minus the net work done by the system.

ΔU = Q - W

Where;

Q, the net heat transfer into the system depends on the pathway

W, the net work done by the system also depends on the pathway

But, ΔU, the change in internal energy is independent of pathway

Therefore, the correct option is "A"

a. the amount of work done on a system is dependent of pathway

Answer: The motion of a ball falling down through the atmosphere, or a model rocket being launched up into the atmosphere are both examples of Newton's first law. The motion of a kite when the wind changes can also be described by the first law.

Explanation:

Answer:

We are given:

m = 1500 kg

initial velocity (u) = 35 m/s

final velocity (v) = 0 m/s

time (t) = 5 seconds

acceleration = a m/s/s

Force (f) = F  newtons

Solving for acceleration:

Using the first equation of motion:

v = u + at

replacing the variables

0 = 35 + a(5)

a = -35/5

a = -7 m/s/s

Force applied by the brakes:

From newton's second law of motion:

F = ma

replacing the variables

F = (1500)(-7)

F = -10500 N

Therefore, the force applied by the brakes is -10500 N, we have a negative sign since the force is being applied opposite to the direction of motion

Answer:

Yes, the number of electrons determines the chemical properties of the atom.

Explanation:

Answer:

Approximately 17.21 seconds

Explanation:

With subtraction, we have the gazelle 18.3 km/h slower than the cheetah, which is about 5.08333 m/s. As the gazelle is 87.5 meters ahead of the cheetah, 87.5 divided by 5.083333333 is about 17.21 seconds.

Answer:

Matter

Explanation:

Because it is solid

Answer:

Solid

Solid < Liquid < Gas

Answer:

Vy = 24.01 [m/s]

Explanation:

To solve this problem we must understand that velocity is a vector and therefore has magnitude and direction, in this way we can decompose the velocity in the components x & y, by means of the trigonometric functions of the sine and cosine of the angle.

For the vertical component, the sine of the angle is used.

Vy = 25.79*sin(68.64)

Vy = 24.01 [m/s]

Answer:

a) 1.4 m/s2

b) 63N

c) 6.66kg

Answer: false

Explanation:

Answer:

Induced emf = 0

Explanation:

An emf can be induced due to the change in magnetic field. It can be given by :

[tex]\epsilon=\dfrac{d\phi}{dt}\\\\\because \phi=BA\cos\theta\\\\\epsilon=\dfrac{d(BA\cos\theta)}{dt}\\\\\epsilon=A\cos\theta\dfrac{dB}{dt}[/tex]

As the loop is placed perpendicular to a uniform magnetic field of 1 Tesla. It means that [tex]\theta=90^{\circ}[/tex] and cos(90) = 0. Hence, the induced emf is equal to 0.

Answer:

give us some further context to answer your question as well

Explanation:

Answer:

when your heart rate is not high than normal or lower than normally

Explanation:

Recovery heart rate is when your heart recovers from a certain heart rate eg high heart rate or even low heart rate this means you heart is now functioning normally .

Answer:

Number of beats per minute the heart drops after exercise.

Complete Question

The complete question is shown on the first uploaded image

Answer:

The value is  [tex]v = 9.18 *10^{6} \ m/s[/tex]

Explanation:

From question we are told that

  The potential  difference is  [tex]\Delta V = 0.24 kV = 0.24 *10^{3} \ V[/tex]

Generally the the non-relativistic speed of these electrons  is mathematically represented as

       [tex]v = \sqrt{\frac{2 * e * \Delta V}{m} }[/tex]

Here  m is the mass of an electron with value [tex]m = 9.11 *10^{-31 } \ kg[/tex]

           e  is the charge on an electron with value  [tex]e = 1.60 *10^{-19} \ C[/tex]

So

        [tex]v = \sqrt{\frac{2 * 1.60 *10^{-19} * 0.24 *10^{3} }{9.11*10^{-31}} }[/tex]

=>   [tex]v = 9.18 *10^{6} \ m/s[/tex]

Complete Question

A 940-g rock is whirled in a horizontal circle at the end of a 1.30-m-long string,  If the breaking strength of the string is 120 N, what's the minimum angle the string can make with the horizontal?

Answer:

The value is [tex]\theta = 4.41^o[/tex]      

Explanation:

From the question we are told that

  The mass of the rock is  [tex]m_r = 940 \ g = 0.94 \ kg[/tex]

   The length of the string is [tex]l = 1.30 \ m[/tex]

    The breaking strength(i.e the maximum tension) on the string is [tex]T = 120 \ N[/tex]

Gnerally the vertical component of the tension experienced by the string is mathematically represented as

     [tex]T_v = T sin(\theta)[/tex]

Generally this vertical component  of tension is equivalent to the weight of the rock

So

     [tex]Tsin (\theta) = mg[/tex]

=>  [tex]\theta = sin^{-1} [\frac{mg}{ T} ][/tex]

=>    [tex]\theta = sin^{-1} [\frac{0.940 *9.8 }{ 120} ][/tex]

=>    [tex]\theta = 4.41^o[/tex]      

Answer:

B. It is B because without this much space for oxygen and blood to flow and go through, we would not survive.

Explanation:

Answer:

The maximum energy that can be transferred to an electron in a single collision of alpha particle is 1.63 keV

Explanation:

let mass of electron, Me = 1

let mass of proton, Mp = 1836Me = 1836

let mass of alpha particle, Ma = 4Mp = 7344

The maximum energy that can be transferred to an electron in a single collision is given by;

[tex]Q_{max} = \frac{4mME}{(M+m)^2}\\\\Q_\alpha_{max} = \frac{4(1)(7344)(3\ MeV)}{(1+7344)^2} = 0.00163 \ MeV = 1.63 \ KeV[/tex]

Therefore, the maximum energy that can be transferred to an electron in a single collision of alpha particle is 1.63 keV

Answer:

Explanation:

The force acting on an object can be found by using the formula

From the question

mass = 1000 g = 1 kg

acceleration = 20 m/s²

We have

force = 20 × 1

We have the final answer as

Hope this helps you