PHYSICS HIGH SCHOOL

A train traveling 80.0 kph is blowing its horn as it approaches a railroad crossing. The horn has a frequency of 300.0 Hz. Assume the speed of sound is 331.5 m/s. What is the observed frequency of the horn?395 Hz

281 Hz

322 Hz

Answers

Answer 1
Answer:

Answer:

322 Hz

Explanation:

v = speed of train approaching the railroad crossing = 80 km/h = 80 x 1000/3600 m/s = 22.22 m/s

V = speed of sound of the horn of train = 331.5 m/s

f = actual frequency of the sound from the horn = 300.0 Hz

f' = observed frequency of the horn

Using Doppler's effect, observed frequency is given as

f' = V f/(V - v)

inserting the values

f' = (331.5) (300.0)/(331.5 - 22.22)

f' = 322 Hz
Answer 2
Answer: the answer to your question is 322 hz
h

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Which is an example of potential energy? a swimmer kicking their legs a car driving on the road an arrow flying at a target a yo-yo in someone’s hand

Answers

Answer: A yo-yo in someone's hand

Explanation:

Potential energy is the energy possessed by a body due to virtue of its position. Kinetic energy is the energy possessed by the body due to virtue of its motion.

A swimmer kicking their legs, a car driving on the road, an arrow flying at a target possess kinetic energy because of their motion. A yo-yo in someone's hand possess elastic potential energy.

Answer:

The answer is D

Explanation:

just trust

A rectangular in-ground pool is 45 feet long, 15.5 feet wide and 5.5 feet deep. How many cubic feet of water does the pool hold?

Answers

Answer: 3836.25 cubic ft.

Explanation: Simply find the volume of the pool. In this case it's a rectangular prism so we use the volume equation for a rectangular prism:  

1) Volume = length x width x height

2) Volume = 45 ft x 15.5 ft x 5.5 ft

3) 3836.25 cubic ft.

If the pitch of the sound coming out from a speaker increases, which is true about the sound wave?

Answers

If the pitch of a sound increases, then we know that its frequency
has increased, and its wavelength has decreased.

Answer:

B

Explanation:

Because If the pitch of a sound increases, then we know that its frequency  

has increased, and its wavelength has decreased.

Secondary evidence is the basis for drawing scientific conclusions.
a. True
b. False

Answers

The answer is false! Hope that helps! :) 

The answer would be, B-False

Ilya and Anya each can run at a speed of 8.90mph and walk at a speed of 3.80mph . They set off together on a route of length 5.00miles. Anya walks half of the distance and runs the other half, while Ilya walks half of the time and runs the other half.a)How long does it take Anya to cover the distance of 5.00miles ?
Express your answer numerically, in minutes.
b)Find Anya's average speed.
Express Anya's average speed save,Anya numerically, in miles per hour
C)How long does it take Ilya to cover the distance?
Express the time tIlya taken by Ilya numerically, in minutes.
d)Now find Ilya's average speed.
Express Ilya's average speed save,Ilya numerically, in miles per hour

Answers

Answer:

Part a)

T = 0.94 hours

Part b)

v_(avg) = 5.32 mph

Part c)

T = 0.79 h

Part d)

v_(avg) = 6.35 mph

Explanation:

Speed while she is running = 8.90 mph

speed while she walk = 3.80 mph

Part a)

Anya walks half the distance

so time to walk

t_1 = (2.5)/(3.80) = 0.66 h

time to cover the distance while she run

t_2 = (2.5)/(8.90) = 0.28 h

total time to cover the distance

T = t_1 + t_2

T = 0.94 hours

Part b)

Average speed is given as

v_(avg) = (d)/(t)

v_(avg) = (5.00 miles)/(0.94)

v_(avg) = 5.32 mph

Part c)

Half the time Llya walks and next half the time she runs

so total distance is given as

d = v_1(T/2) + v_2(T/2)

so we have

5.00 = 8.90(T/2) + 3.80(T/2)

T = 0.79 h

Part d)

Average speed is given as

v_(avg) = (d)/(t)

v_(avg) = (5.00 miles)/(0.79)

v_(avg) = 6.35 mph

Ask a questioWhat are powers called that the framers of the Constitution felt existed and were expected to be held by the national government due to historical precedence and common practice?a. expressed
b. implied
c. intended
d. inherent n here.

Answers

The powers that the framers of the Constitution felt existed and were expected to be held by the national government due to historical precedence and common practice were called D) inherent. 
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