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aev [14]
3 years ago
15

From a vantage point very close to the track at a stock car race, you hear the sound emitted by a moving car. You detect a frequ

ency that is 0.86 times as small as the frequency emitted by the car when it is stationary. The speed of sound is 343 m/s. What is the speed of the car?
Physics
1 answer:
V125BC [204]3 years ago
6 0

Answer:

55.8 m/s

Explanation:

f = Actual frequency of sound emitted by car

f' = frequency observed when the car moves = (0.86)f

V = Speed of sound = 343 m/s

v = Speed of car

Frequency observed is given as

f' = \frac{Vf}{V+v}

(0.86) = \frac{(343)}{343 + v}\\(0.86) = \frac{(343)}{343 + v}\\294.98 + (0.86) v = 343 \\v = 55.8 ms^{-1}

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Glass absorbs ultraviolet (UV) rays from the Sun. Would a fraction of the incident UV light be reflected from the air/glass boun
fiasKO [112]

Answer:

Yes

Explanation:

Any transparent surface in practical is neither a perfect absorber of electromagnetic waves neither a perfect reflector. Generally all the transparent surfaces reflect some amount of irradiation and the other parts are absorbed and transmitted.

<u>That is given by as relation:</u>

\alpha+\rho+\tau=1

where:

\alpha= absorptivity which is defined as the ratio of the absorbed radiation to the total irradiation

\rho= reflectivity is defined as the ratio of reflected radiation to the total irradiation

\tau= transmittivity is defined as the ratio of total transmitted radiation to the total irradiation

6 0
3 years ago
A ball with a mass of 3.1 kg is moving in a uniform circular motion upon a horizontal surface. The ball is attached at the cente
inessss [21]

Answer:

3.46 seconds

Explanation:

Since the ball is moving in circular motion thus centripetal force will be acting there along the rope.

The equation for the centripetal force is as follows -

F=\frac{mv^2}{r}

Where, m is the mass of the ball, v is the speed and r is the radius of the circular path which will be equal to the length of the rope.

This centripetal force will be equal to the tension in the string and thus we can write,

20.4 = \frac{3.1\times v^2}{2}

and, v^2 = 13.16

Thus, v = 3.63 m/s.

Now, the total length of circular path = circumference of the circle

Thus, total path length = 2πr = 2 × 3.14 × 2 = 12.56 m

Time taken to complete one revolution = \frac{\text {Path length} }{\text {Speed}} = \frac{12.56}{3.63} = 3.46 seconds.

Thus, the mass will complete one revolution in 3.46 seconds.

4 0
2 years ago
In a compound microscope, the objective has a focal length of 1.0 cm, the eyepiece has a focal length of 2.0 cm, and the tube le
expeople1 [14]

Answer:

The  value  is   m \approx   310

Explanation:

From the question we are told that

     The  focal length of the objective is  f_o =  1.0 \ cm

    The  focal length of the eyepiece is  f_e  =  2.0 \  cm

    The  tube length is  L  =  25 \  cm

Generally the magnitude of the overall magnification is mathematically represented as

            m =  m_o  *  m_e

Where  m_o is the objective magnification which is mathematically represented as

        m_o  =  \frac{L}{f_o }

=>      m_o  =  \frac{25}{1 }

=>      m_o  =  25

m_e is the eyepiece magnification which is mathematically evaluated as

     m_e  =  \frac{L }{f_e }

     m_e  =  \frac{25 }{ 2}

      m_e  =  12.5 \  cm

So

    m =  25 * 12.5

     m \approx   310

6 0
3 years ago
ID like to say thx everyone who is on brainly u guys helped me get through my quiz so thx
VARVARA [1.3K]

Answer:

I want to know how your experience has been on brainly. I hope it is good. I really like spending time helping others here. If you have any other questions please ask me :)

Explanation:

8 0
2 years ago
Read 2 more answers
A parallel-plate capacitor, with air dielectric, is charged by a battery, after which the battery is disconnected. A slab of gla
Diano4ka-milaya [45]

Complete Question

A parallel-plate capacitor, with air dielectric, is charged by a battery, after which the battery is disconnected. A slab of glass dielectric is then slowly inserted between the plates. As it is being inserted,  

A :

a force repels the glass out of the capacitor.  

B :

a force attracts the glass into the capacitor.    

C :

no force acts on the glass.      

D :

a net charge appears on the glass.      

E :

the glass makes the plates repel each other.

Answer:

The correct option is B

Explanation:

Generally when the glass dielectric is slowly inserted between the plated,

The positive plate of the capacitor will induce a negative charge on the glass while the negative  plate of the capacitor will induce a positive charge on glass which a electric field that posses an electric force that will attract the glass

3 0
3 years ago
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