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mario62 [17]
3 years ago
13

An opera singer in a convertible sings a note at 600 Hz while cruising down the highway at 90 km/h. What is the frequency heard

by
a. A person standing beside the road in front of the car?
b. A person standing beside the road behind the car?
Physics
1 answer:
Taya2010 [7]3 years ago
5 0

To solve this problem we will apply the concepts related to the Doppler effect. The general expression to apply the Doppler effect is given by the function:

f = (\frac{f_0}{1\pm v_s/v})

Here,

f_0 = Original Frequency

f = Observed Frequency

v_s = Speed of the object

v = Speed of the sound wave

PART A)

Converting the velocity to SI units we have,

v = 90km/h(\frac{3600s}{1h})(\frac{1000m}{1km})

v = 25m/s

Replacing at the equation we have,

f = (\frac{f_0}{1 - v_s/v})

f =  (\frac{600Hz}{1-25/343})

f = 650Hz

Therefore the frequency for a person standing beside the road in front of the car is 650Hz

PART B) The frequency for a person standing beside the road behind the car would be,

f = (\frac{f_0}{1+v_s/v})

f = (\frac{600Hz}{1-25/343})

f = 560Hz

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Andrew [12]

Answer:

I hope this helps.

Explanation:

It's important to know the location of an active fault in order to determine the magnitude of the expected earthquake. There is a chance than an inactive fault can become active again. It's important that we take the locations into account in order to be prepared and ready for if it occurs.

5 0
3 years ago
One type of slingshot can be made from a length of rope and a leather pocket for holding the stone. The stone can be thrown by w
grigory [225]

Answer:

15.66 rad/s

Explanation:

The vertical motion and horizontal motion are independent of each other.

t = √ ( 2 s/ g) where t = time for the ball to reach the ground and s is the height of the cliff = 18.0 m

t = √ ( 36 / 9.81 ) = 1.916 secs

horizontal distance travel = ut where u is the horizontal velocity of the stone = 30 × r (radius)

tangential velocity V = angular velocity ( ω) × radius

distance traveled = ω × r × t = 30 × r

radius cancelled on both side

ω = 30 / 1.9156 = 15.66 rad/s

4 0
3 years ago
A 34.0 %-efficient electric power plant produces 800 MW of electric power and discharges waste heat into 20∘C ocean water. Suppo
mojhsa [17]

Answer:

77647

Explanation:

\eta = Efficiency = 34%

Power used in 1 home = 0.02 MW

Total power is

P=\dfrac{800}{\eta}\\\Rightarrow P=\dfrac{800}{0.34}\\\Rightarrow P=2352.94117\ MW

Waste of power

2352.94117-800=1552.94117\ W

Number of homes would be given by

n=\dfrac{1552.94117}{0.02}=77647.0585\ homes

The number of homes that could be heated with the waste heat of this one power plant is 77647

8 0
2 years ago
A 0.29 kg particle moves in an xy plane according to x(t) = - 19 + 1 t - 3 t3 and y(t) = 20 + 7 t - 9 t2, with x and y in meters
Artist 52 [7]

Answer:

Part a)

F = 7.76 N

Part b)

\theta = -137.7 degree

Part c)

\theta = -127.7 degree

Explanation:

As we know that acceleration is rate of change in velocity of the object

So here we know that

x = -19 + t - 3t^3

y = 20 + 7t - 9t^2

Part a)

differentiate x and y two times with respect to time to find the acceleration

a_x = \frac{d^2}{dt^2}(-19 + t - 3t^3)

a_x = \frac{d}{dt}(0 +1 - 9t^2)

a_x = -18t

a_y = \frac{d^2}{dt^2}(20 + 7t - 9t^2)

a_y = \frac{d}{dt}(0 +7 - 18t)

a_y = -18

Now the acceleration of the object is given as

\vec a = (-18t)\hat i + (-18)\hat j

at t= 1.1 s we have

\vec a = -19.8 \hat i - 18 \hat j

now the net force of the object is given as

\vec F = m\vec a

\vec F = (0.29 kg)(-19.8 \hat i - 18 \hat j)

\vec F = -5.74 \hat i - 5.22 \hat j

now magnitude of the force will be

F = \sqrt{5.74^2 + 5.22^2} = 7.76 N

Part b)

Direction of the force is given as

tan\theta = \frac{F_y}{F_x}

tan\theta = \frac{-5.22}{-5.74}

\theta = -137.7 degree

Part c)

For velocity of the particle we have

v_x = \frac{dx}[dt}

v_x = (0 +1 - 9t^2)

v_y = \frac{dy}{dt}

v_y = (0 +7 - 18t)

now at t = 1.1 s

\vec v = -9.89\hat i - 12.8 \hat j

now the direction of the velocity is given as

\theta = tan^{-1}(\frac{v_y}{v_x})

\theta = tan^{-1}(\frac{-12.8}{-9.89})

\theta = -127.7 degree

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3 years ago
Which of the following is the best explanation of work
Hunter-Best [27]

Answer:

b

Explanation:

b

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