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FrozenT [24]
3 years ago
5

You are standing at a subway platform when a subway passes, sounding its whistle. If you observe the whistle to be at 12750Hz wh

en it is approaching you and at 10750Hz after it passes,
Physics
1 answer:
adell [148]3 years ago
5 0

As per doppler's Effect of sound we can say when subway is approaching the platform we will have

f_1 = f_o* \frac{v}{v- v_s}

12750 = f_o* \frac{340}{340 - v_s}

Similarly we can find the frequency when subway is passing away with same speed from us

f_2 = f_o* \frac{v}{v + v_s}

10750 * f_o* \frac{340}{340 + v_s}

now we can find the ratio of two

\frac{12750}{10750} = \frac{340 + v_s}{340 - v_s}

1.186*(340 - v_s) = 340 + v_s

403.26 - 1.186 v_s = 340 + v_s

63.26 = 2.186 v_s

v_s = \frac{63.26}{2.186}

v_s = 28.94 m/s

So the speed of subway is 28.94 m/s

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Answer:

Electric field at a point ( x , y , z) is E=-2yz^2-2xz^2-4xyz .

Explanation:

Given :

Electric potential in the region is , V = 2xyz^2\ .

We need to find the electric field .

We know , electric field , E=-\dfrac{dV}{dr}  { Here r is distance }

In coordinate system ,

E=-\dfrac{dV}{\delta x }-\dfrac{dV}{\delta y }-\dfrac{dV}{\delta z }  { \delta is partial derivative }

Putting all values we get ,

E=-\dfrac{2xyz^2}{\delta x }-\dfrac{2xyz^2}{\delta y }-\dfrac{2xyz^2}{\delta z }\\\\E=-2yz^2-2xz^2-4xyz

Hence , this is the required solution.

3 0
2 years ago
How much work is done when a 30 kg mass is to be lifted through a height 6m?(1kg=9.8N​
rusak2 [61]

we know 1kg=9.8N​ so 30 kg= 30 x 9.8 = 294 N

work is done when a 30 kg mass is to be lifted through a height 6m :

A = 294 x 6 = 1764 J

ok done. Thank to me :>

8 0
2 years ago
Which statement accurately describes the charge of the nucleus of an atom?
Aleksandr [31]

Answer:

A. The nucleus can be either positively charged or neutral.

Explanation:

The nucleus of an atom contains protons and neutrons only. Whereas electrons revolve around the nucleus. Protons are positively charged, neutrons have no charge and electrons are negatively charged.

3 0
3 years ago
Calculate the volume of 19 kilograms of petrol if the density of petrol is 800 kg/m?​
earnstyle [38]

Answer:

i hope this will help you :)

Explanation:

mass=19kg

density=800kg/m³

volume=?

as we know that

density=mass/volume

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volume=mass/density

putting the values

volume=19kg/800kg/m³

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6 0
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Answer: 200 J

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4 0
3 years ago
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