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Sergio039 [100]
3 years ago
8

1. Which of the following statements about mechanical waves is true?

Physics
1 answer:
uranmaximum [27]3 years ago
5 0
1) <span>a. mechanical waves require a medium to travel through
In fact, mechanical waves cannot travel trough empty space, but they always require a medium for their propagation. (on the contrary, electromagnetic waves can also travel through empty space)

2) d</span><span>. gamma rays
In fact, gamma rays are the radiations with shortest wavelength on the electromagnetic spectrum (range in the picometer). Correspondingly, this is the radiation with highest energy, because the energy of the radiation is inversely proportional to its wavelength, according to:
</span>E=h \frac{c}{\lambda}
where h is the planck constant, c the speed of light and \lambda the wavelength.

3) <span>d. Infrared have lower frequency than x-rays
In fact, infrared radiation has frequency in the range of the THz (terahertz, </span>10^{12} Hz), while x-rays have frequency in the range of hundreds of PHz (Petahertz, 10^{15}Hz).

4) <span>d. parallel
In longitudinal waves, the oscillations of the wave (such as the motion of the particles in a compression wave) occur in the direction parallel to the direction of propagation of the wave itself.

5) </span><span>c. gases
Sound travels slowest in gases. In fact, the speed of sound is proportional to the density of the medium: the more dense the medium is, the faster is the sound in that medium, and vice-versa. Since gases are less dense than liquids and solids, sound travels slowest in gases. The reason is that sounds propagates through the oscillations of the molecules of the medium; if the medium is less dense (such as in gases), it takes more time to transmit the sound through the medium itself.</span>
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Suppose you are standing at the exact center of a park surrounded by a circular road. An ambulance drives completely around this
vladimir2022 [97]

Answer: The pitch of the sound does not change.

Explanation: The pitch of sound wave is dependent on the frequency of the sound wave. The frequency of sound wave when their is a relative motion between an observer and a source is given by Doppler effect.

Doppler effect is a mathematical equation that gives the relationship between the observed frequency by an observer from any sound source and the relative motion between the observer and the source.

Mathematically,

f'= (v+v') /(v-vs) * f

Where f' = observed frequency of sound wave

v= speed of sound in air

v'= velocity of observer relative to sound source

vs= velocity of sound source relating to observer

f= frequency of sound produced by source

The observer is at the center, thus the distance between the observer and the source is constant (according to mensuration, the radius is constant for any given circle and since the car is moving along a circular path and the observer is at the center, thus the distance between them is constant), thus making the relative velocity between the observer and the source constant (vs=constant).

Also the frequency of sound wave produce by the source is a constant (f=constant)

The speed of sound in air is also a constant (v=336m/s)

The observer is standing at the center thus he is not moving, hence the relative motion between observer and source is also constant (v'=constant)

Since all parameters are constant, then the observed frequency will be constant too.



4 0
3 years ago
2) What did Rutherford discover in his experiment?<br> a) nucleus<br> b) electrons<br> c) neutrons
OlgaM077 [116]
A) nucleus because some aims reflected off the gold foil proving that there was something bigger inside the atom hence discovering the nucleus
5 0
2 years ago
A vehicle that goes from 5m/s to 45m/s in 8s. what is its acceleration?
GaryK [48]

Answer: 5m/s^2

Explanation:

V= 45m/s

U = 5m/s

t = 8s

a =?

V = u + at

45 = 5 + 8a

8a = 45 — 5

8a = 40

a = 40 / 8

a = 5m/s^2

3 0
3 years ago
calculate the frequency and time period of sound wave of 35 m wave length propagating at a speed of 3500m/s​
zheka24 [161]

Answer:

Frequency = 100 Hz

Time period = 0.01 sec

Explanation:

f= 3500/35 = 100

T = 1/f = .01

5 0
2 years ago
A penny has a mass of 2.50 g, a diameter of 19.55 mm, and a thickness of 1.55 mm. Calculate the density of the material from whi
Dmitry [639]
Density = (mass) divided by (volume)

We know the mass (2.5 g).  We need to find the volume.

The penny is a very short cylinder.
The volume of a cylinder is (π · radius² · height).
The penny's radius is 1/2 of its diameter = 9.775 mm.
The 'height' of the cylinder is the penny's thickness = 1.55 mm.

Volume  =  (π) (9.775 mm)² (1.55 mm)

             =  (π) (95.55 mm²) (1.55 mm)

             =  (π) (148.1 mm³)

             =        465.3 mm³

We know the volume now.  So we could state the density of the penny,
but nobody will understand what we have.  Here it is:

         mass/volume = 2.5 g / 465.3 mm³  =  0.0054 g/mm³  .

Nobody every talks about density in units of ' gram/(millimeter)³ ' .
It's always ' gram / (centimeter)³ '.
So we have to convert our number for the volume.

                         (0.0054  g/mm³)  x  (10 mm / cm)³

                 =      (0.0054 x 1,000)  g/cm³

                 =          5.37  g/cm³  .

This isn't actually very close to what the US mint says for the density
of a penny, but it's in a much better ball park than 0.0054 was.
4 0
3 years ago
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