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Alenkinab [10]
3 years ago
7

A commuter train passes a passenger platform at a constant speed of 39.6 m/s. The train horn is sounded at its characteristic fr

equency of 346 Hz. (a) What overall change in frequency is detected by a person on the platform as the train moves from approaching to receding
Physics
1 answer:
aleksandr82 [10.1K]3 years ago
4 0

Answer:

Explanation:

We shall apply Doppler's effect to solve the problem .

Formula for apparent frequency for a source of sound approaching an observer is as follows .

f₁ = f₀ V / (V - v )

where f₁ and f₀ are apparent and real frequency of source , V and v is velocity of sound and velocity of approaching source respectively .

Putting the given values and knowing that speed of sound is 340 m /s

f₁ =346x 340 / (340 - 39.6 )

f₁ = 391.6 Hz

In case of receding train , the formula is

f₂ = f₀ V / (V + v )

Putting the values

f₂ = 346x 340 / (340 + 39.6 )

= 309.9 Hz

Change in frequency =  391.6 - 309.9

= 81.7 Hz .

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2 years ago
27. The traffic officer issued violation tickets to traffic
Evgen [1.6K]

Answer:

27: 85

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Explanation:

27:68=80

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3 0
3 years ago
Andrea and Chuck are riding on a merry-go-round. Andrea rides on a horse at the outer rim of the circular platform, twice as far
marta [7]

a) Their angular speeds are the same

b) Andrea's tangential speed is twice the value of Chuck's tangential speed

Explanation:

a)

The angular speed of Andrea and Chuck is the same.

Let's call \omega the angular speed at which the merry-go-round is rotating. We know that the angular speed is defined as:

\omega= \frac{2\pi}{T}

where

2 \pi is the angular displacement covered in one revolution

T is the period of revolution

The merry go round is a rigid body, so all its point cover the same angular displacement in the same time: this means that it doesn't matter where Andrea and Chuck are located along the merry-go-round, their angular speed will still be the same.

b)

For an object in circular motion, the tangential speed is given by

v=\omega r

where

\omega is the angular speed

r is the distance from the centre of rotation

Here let's call r_c the distance at which Chuck is rotating, so his tangential speed is

v_c = \omega r_c

Now we know that Andrea is rotating twice as far from the centre, so at a distance of

r_a = 2 r_c

So his tangential speed is

v_a = \omega r_a = \omega (2 r_c) = 2(\omega r_c) = 2 v_c

So, Andrea's tangential speed is twice the value of Chuck's tangential speed.

Learn more about circular motion:

brainly.com/question/2562955

brainly.com/question/6372960

#LearnwithBrainly

5 0
3 years ago
The speed of a box traveling on a horizontal friction surface changes from vi = 13 m/s to vf = 11.5 m/s in a distance of d = 8.5
ValentinkaMS [17]

The average power supplied to the box by friction while it slows from 13 m/s to 11.5 m/s is 3.24 W.

<h3>Acceleration of the box</h3>

The acceleration of the box is calculated as follows;

vf² = vi² + 2as

a = (vf² - vi²)/2s

a = (11.5² - 13²) / (2 x 8.5)

a = -2.16 m/s²

<h3>Time of motion of the box</h3>

The time taken for the box to travel is calculated as follows;

a = (vf - vi)/t

t = (vf - vi) / a

t = (11.5 - 13) / (-2.16)

t = 0.69 s

<h3>Average power supplied by the friction</h3>

P = Fv

P = (ma)(vf - vi)

P = (1 x -2.16) x (11.5 - 13)

P = 3.24 W

Thus, the average power supplied to the box by friction while it slows from 13 m/s to 11.5 m/s is 3.24 W.

Learn more about average power here: brainly.com/question/19415290

#SPJ1

7 0
2 years ago
Where were most of the elements "forged" on the periodic table ​
klemol [59]
<h2>Answer: Stars</h2>

Most of the chemical elements of the Periodic Table were formed or "<em>forged</em>" in the different types of stars that exists in the universe in their different phases of life.

For example, a young star is composed mainly of Hydrogen, the simplest chemical substance and <u>the first in the Periodic Table</u>; being this the element that leads to the other known elements. Taking into account that the two components of each hydrogen atom (1 proton and 1 electron) are separated, the great pressure within the star manages to merge (fuse) two protons.

What does this mean?

Well, sometimes a proton captures an electron and becomes a neutron, but when two protons and two neutrons join together, they form the Helium nucleus, which is <u>the second element in the periodic table</u>. Then, when two helium nuclei join and form the nucleus of another element, Beryllium and so on.

So, by means of the nuclear fusion process the nuclei of most of the  elements lighter than Iron (which is the chemical element 26 of the periodic table) can be formed.

Now, elements that are heavier than Iron can be forged within the stars through the capture of neutrons. In this way, the collapse of the star's center core occurs so quickly that it generates huge shock waves that eject the outer layers of the star into space becoming a <u>supernova</u>. Then, it is during the few seconds of collapse that the specific pressure and temperature conditions in the supernova are created and allow heavier elements to be generated and expelled as interstellar dust and gas.

In this sense, with the explosion of more<u> massive stars</u> and <u>white dwarfs</u> other chemical elements are formed, as well as others that are formed by <u>dying stars of low mass</u> and <u>neutron stars</u>.

However, it should be noted that there are also chemical elements that are artificially formed in experimental fusion nuclear reactors.

4 0
3 years ago
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