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alex41 [277]
3 years ago
12

Two fire trucks have sirens that emit waves of the same frequency. As the fire trucks approach a person, the person hears a high

er frequency from truck X than from truck Y.
1. Which of the following statements about truck X can be correctly inferred from this information?
A) It is traveling faster than truck Y.
B) It is closer to the person than truck Y.
C) It is speeding up, and truck Y is slowing down.
Physics
1 answer:
Mumz [18]3 years ago
5 0

Answer:

Only option A is correct

Explanation:

From the concept of Doppler effect, only speed matters. Thus, the faster a vehicle is moving, the closer together the sound waves get compressed and the higher the frequency. For example, for a very fast vehicle traveling at the speed of sound; the compressions are all right on top of each other. Thus, faster speed means closer compressions and higher frequencies. Hence, option only option A must be true because X is a higher frequency and so it must be going faster. The distance to the person will affect the volume but will not the pitch so Option B is not correct. Option C too is not correct because It doesn’t matter whether you are speeding up or slowing down, it only matters who is going faster. For example, from option c concept, if truck X was going 10 m/h and speeding up while truck Y was going 50 mph and slowing down, it would not meet the requirement that X has a higher frequency because only actual speed matters, not what is happening to that speed. Thus only option A is the correct answer

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(pleases show work)
Feliz [49]

a. 46 m/s east

The jet here is moving with a uniform accelerated motion, so we can use the following suvat equation to find its velocity:

v=u+at

where

v is the velocity calculated at time t

u is the initial velocity

a is the acceleration

The jet in the problem has, taking east as positive direction:

u = +16 m/s  is the initial velocity

a=+3 m/s^2  is the acceleration

Substituting t = 10 s, we find the final velocity of the jet:

v=16 + (3)(10)=46 m/s

And since the result is positive, the direction is east.

b. 310 m

The displacement of the jet can be found using another suvat equation

s=ut+\frac{1}{2}at^2

where

s is the displacement

u is the initial velocity

a is the acceleration

t is the time

For the jet in this problem,

u = +16 m/s  is the initial velocity

a=+3 m/s^2  is the acceleration

t = 10 s is the time

Substituting into the equation,

s=(16)(10)+\frac{1}{2}(3)(10)^2=310 m

4 0
3 years ago
Total mechanical energy (The sum of kinetic and potential energy
victus00 [196]

Answer:

Emechanical=mgh+\frac{1}{2}mν²

Explanation:

The equation for the total mechanical energy is:

Emechanical=Epotential+Ekinetic

In which,

Epotential=mgh; m: mass of the body, g: gravity; h: height

Ekinetic=\frac{1}{2}mν²; m: mass of the body, ν: velocity of the body

So,

Emechanical=mgh+\frac{1}{2}mν²

5 0
3 years ago
Mr. Smith used 606 kWh for the month. If the service charge was $61.37 (see back page of the bill), what is the approximate char
Murrr4er [49]

Answer:

.10/KWh

Explanation:

divide 606 by 61.37 and you get .1012...

7 0
3 years ago
When the displacement of a mass on a spring is 12 a the half of the amplitude, what fraction of the mechanical energy is kinetic
Sveta_85 [38]
You know that when the displacement is equal to the amplitude (A), the velocity is zero, which implies that the kinetic energy (KE) is zeero, so the total mechanical energy (ME) is the potential energy (PE).

And you know that the potential energy, PE, is [ 1/2 ] k (x^2)

Then, use x = A, to calculate the PE in the point where ME = PE.

ME = PE = [1/2] k (A)^2.

At half of the amplitude, x = A/2 => PE = [ 1/2] k (A/2)^2

=> PE = [1/4] { [1/2]k(A)^2 } = .[1/4] ME

So, if PE is 1/4 of ME, KE is 3/4 of ME.

And the answer is 3/4


7 0
3 years ago
Answers are - <br><br>A 235 N<br><br>B 376 N<br><br>C 271 N<br><br>D 188 N<br><br>E 470 N
amm1812

Answer:

C

Explanation:

8 0
3 years ago
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