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Anastaziya [24]
2 years ago
9

Have you heard an ambulance, police car, or fire truck recently? Did you notice that the pitch of the siren changed as it approa

ched you and then again as it moved away? What concept explains this change or shift in sound waves?
Physics
2 answers:
Tanzania [10]2 years ago
5 0
The Doppler Effect is the change in frequency or wavelength of a wave for an observer moving relative to its source. It is named after the Austrian physicist Christian Doppler.
Bumek [7]2 years ago
3 0

Answer: Doppler effect

Explanation:

When there is relative motion between source and listener of sound, the apparent frequency heard by the listener is different from the frequency of the source. When the source and the listener are moving closer, the apparent frequency increases and when they move apart, there is decrease in the apparent frequency. This is Doppler's effect.

The wave-fronts move closer as the source and listener approach closer to each other. Thus, the observed frequency is greater than the actual. The pitch depends on frequency, greater is the pitch.

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Does the thickness of the wire affect the strength of an electroscope
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It probably does. I'm not 100% sure about it, but a thicker wire would increase the number of positive and negative charges in it.
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3 years ago
A man stands still on a moving walkway that is going at a speed of 0.3 m/s to the south. What is the velocity of the man accordi
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The velocity is 0.3 m/s South.
3 0
2 years ago
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A long, straight, vertical wire carries a current upward. Due east of this wire, in what direction does the magnetic field point
AlexFokin [52]

The magnetic field of the wire will be directed towards west. Using right thumb rule one can get the direction of field lines.

5 0
2 years ago
Which wave causes the medium to vibrate only in a direction not parallel to the waves motion?
Paha777 [63]

The correct answer to the question is : Transverse wave.

EXPLANATION :

Before going to answer this question, first we have to understand the longitudinal and transverse wave.

LONGITUDINAL WAVE : A longitudinal wave is a mechanical wave in which the direction of vibration of particles is parallel to the direction of wave propagation. It moves in the form of compression and rarefaction.

For instance, sound wave.

TRANSVERSE WAVE : A transverse wave is a mechanical wave in which the direction of vibration of particles is perpendicular to the direction of wave propagation. It moves in the form of crests and troughs.

For instance, the wave created in a pond when a stone is dropped into it.

Hence, the correct answer of this question is transverse wave.

4 0
3 years ago
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Continuous and aligned fiber-reinforced composite with cross-sectional area of 340 mm2 (0.53 in.2) is subjected to a longitudina
Alecsey [184]

(a) 23.4

The fiber-to-matrix load ratio is given by

\frac{F_f}{F_m}=\frac{E_f V_f}{E_m V_m}

where

E_f = 131 GPa is the fiber elasticity module

E_m = 2.4 GPa is the matrix elasticity module

V_f=0.3 is the fraction of volume of the fiber

V_m=0.7 is the fraction of volume of the matrix

Substituting,

\frac{F_f}{F_m}=\frac{(131 GPa)(0.3)}{(2.4 GPa)(0.7)}=23.4 (1)

(b) 44,594 N

The longitudinal load is

F = 46500 N

And it is sum of the loads carried by the fiber phase and the matrix phase:

F=F_f + F_m (2)

We can rewrite (1) as

F_m = \frac{F_f}{23.4}

And inserting this into (2):

F=F_f + \frac{F_f}{23.4}

Solving the equation, we find the actual load carried by the fiber phase:

F=F_f (1+\frac{1}{23.4})\\F_f = \frac{F}{1+\frac{1}{23.4}}=\frac{46500 N}{1+\frac{1}{23.4}}=44,594 N

(c) 1,906 N

Since we know that the longitudinal load is the sum of the loads carried by the fiber phase and the matrix phase:

F=F_f + F_m (2)

Using

F = 46500 N

F_f = 44594 N

We can immediately find the actual load carried by the matrix phase:

F_m = F-F_f = 46,500 N - 44,594 N=1,906 N

(d) 437 MPa

The cross-sectional area of the fiber phase is

A_f = A V_f

where

A=340 mm^2=340\cdot 10^{-6}m^2 is the total cross-sectional area

Substituting V_f=0.3, we have

A_f = (340\cdot 10^{-6} m^2)(0.3)=102\cdot 10^{-6} m^2

And the magnitude of the stress on the fiber phase is

\sigma_f = \frac{F_f}{A_f}=\frac{44594 N}{102\cdot 10^{-6} m^2}=4.37\cdot 10^8 Pa = 437 MPa

(e) 8.0 MPa

The cross-sectional area of the matrix phase is

A_m = A V_m

where

A=340 mm^2=340\cdot 10^{-6}m^2 is the total cross-sectional area

Substituting V_m=0.7, we have

A_m = (340\cdot 10^{-6} m^2)(0.7)=238\cdot 10^{-6} m^2

And the magnitude of the stress on the matrix phase is

\sigma_m = \frac{F_m}{A_m}=\frac{1906 N}{238\cdot 10^{-6} m^2}=8.0\cdot 10^6 Pa = 8.0 MPa

(f) 3.34\cdot 10^{-3}

The longitudinal modulus of elasticity is

E = E_f V_f + E_m V_m = (131 GPa)(0.3)+(2.4 GPa)(0.7)=41.0 Gpa

While the total stress experienced by the composite is

\sigma = \frac{F}{A}=\frac{46500 N}{340\cdot 10^{-6}m^2}=1.37\cdot 10^8 Pa = 0.137 GPa

So, the strain experienced by the composite is

\epsilon=\frac{\sigma}{E}=\frac{0.137 GPa}{41.0 GPa}=3.34\cdot 10^{-3}

3 0
3 years ago
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