1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
Naddika [18.5K]
3 years ago
11

A bat is flitting about in a cave, navigating via ultrasonic bleeps. Assume that the sound emission frequency of the bat is 38.9

kHz. During one fast swoop directly toward a flat wall surface, the bat is moving at 0.015 times the speed of sound in air. What frequency does the bat hear reflected off the wall?
Physics
1 answer:
Alex787 [66]3 years ago
7 0

Answer:

40085 Hz

Explanation:

We are given; Sound frequency emmision of bat;f = 38.9 kHz = 38900 Hz

Bat is moving at 0.015 times the speed of sound in air.

Speed of sound in air = 343 m/s

The formula for waves reflected off the wall is calculated from Doppler equation as:

f' = f(v + v_d)/(v - v_s)

Where;

f is the frequency = 38900 Hz

f' is the detected frequency,

v_d is the velocity of the detector = 0.015 × 343 = 5.145

v_s is the velocity of the source = 0.015 × 343 = 5.145 m/s

v is the velocity of the sound = 343 m/s

Thus;

f' = 38900(343 + 5.145)/(343 - 5.145)

f' ≈ 40085 Hz

You might be interested in
A mass that weight stretches a spring . The system is acted on by an external force . If the mass is pushed up and then released
olchik [2.2K]

Answer:

x = A cos wt

Explanation:

To determine the position we are going to solve Newton's second law

             F = m a

           

Spring complies with Hooke's law

          F = -k x

And the acceleration of defined by

          a = d²x / dt²

         

We substitute

        - k x = m d²x / dt²

         dx² / dt² + k/m  x = 0

Let's call

           w² = k / m

The solution to this type of differential equation is

           x = A cos (wt + Ф)

Where A is the initial block displacement and the phase angle fi is determined by or some other initial condition.

In this case the body is released so that at the initial speed it is zero

From which we derive this expression

         v = dx / dt = a w sin ( wt + Ф)

         

As the System is released for t = 0 the speed is v = 0

         v = sin Ф = 0

Therefore Ф = 0

And the equation of motion is

         x = A cos wt

4 0
3 years ago
A local FM radio station broadcasts at a frequency of 97.3 MHz. Calculate the energy of the frequency at which they are broadcas
levacccp [35]

Answer:

6.45×10¯²⁶ J

Explanation:

From the question given above, the following data were obtained:

Frequency (f) = 97.3 MHz

Energy (E) =?

Next, we shall convert 97.3 MHz to Hz. This can be obtained as follow:

1 MHz = 1×10⁶ Hz

Therefore,

97.3 MHz = 97.3 MHz × 1×10⁶ Hz / 1 MHz

97.3 MHz = 9.73×10⁷ Hz

Thus, 97.3 MHz is equivalent to 9.73×10⁷ Hz.

Finally, we shall determine the energy at which the frequency is broadcasting. This can be obtained as follow:

Frequency (f) = 9.73×10⁷ Hz

Planck's constant (h) = 6.63×10¯³⁴ Js

Energy (E) =?

E = hf

E = 6.63×10¯³⁴ × 9.73×10⁷

E = 6.45×10¯²⁶ J

Therefore, the energy at which the frequency is broadcasting is 6.45×10¯²⁶ J

5 0
3 years ago
A heat engine accepts 200,000 Btu of heat from a source at 1500 R and rejects 100,000 Btu of heat to a sink at 600 R. Calculate
diamong [38]

To solve the problem it is necessary to apply the concepts related to the conservation of energy through the heat transferred and the work done, as well as through the calculation of entropy due to heat and temperatra.

By definition we know that the change in entropy is given by

\Delta S = \frac{Q}{T}

Where,

Q = Heat transfer

T = Temperature

On the other hand we know that by conserving energy the work done in a system is equal to the change in heat transferred, that is

W = Q_{source}-Q_{sink}

According to the data given we have to,

Q_{source} = 200000Btu

T_{source} = 1500R

Q_{sink} = 100000Btu

T_{sink} = 600R

PART A) The total change in entropy, would be given by the changes that exist in the source and sink, that is

\Delta S_{sink} = \frac{Q_{sink}}{T_{sink}}

\Delta S_{sink} = \frac{100000}{600}

\Delta S_{sink} = 166.67Btu/R

On the other hand,

\Delta S_{source} = \frac{Q_{source}}{T_{source}}

\Delta S_{source} = \frac{-200000}{1500}

\Delta S_{source} = -133.33Btu/R

The total change of entropy would be,

S = \Delta S_{source}+\Delta S_{sink}

S = -133.33+166.67

S = 33.34Btu/R

Since S\neq   0 the heat engine is not reversible.

PART B)

Work done by heat engine is given by

W=Q_{source}-Q_{sink}

W = 200000-100000

W = 100000 Btu

Therefore the work in the system is 100000Btu

4 0
4 years ago
After pollination where does a seed grow in a flower?
ozzi

Answer:

the center of the flower or the ovary

3 0
4 years ago
Zeros are always considered significant digits when they are to the left of the decimal point
maksim [4K]

Answer:

Zeros to the left of a decimal can be insignificant place holders, such as in 0.043 (two significant figures).

They can be significant if they are between two digits who themselves are significant, such as in 101.000 (three significant figures).

In the case of a number like 1,000 we can see there is only one significant figure. The zero digits are not between sigfigs.

7 0
4 years ago
Other questions:
  • A sample of helium has a volume of 12.7 m3. The temperature is raised to 323 K at which time the gas occupies 32.5 m3? Assume pr
    14·2 answers
  • A transform boundary occurs where two tectonic plates _____.?
    5·2 answers
  • How can people save money by using solar power in their home​
    15·1 answer
  • How are the three lines of defense the same
    12·2 answers
  • Approximately how many kelvins are equal to 60 c? a. 289k b. 323k c. 333k d. 413k
    9·2 answers
  • Suppose we could shrink the Earth without changing its mass. At what fraction of its current radius would the free-fall accelera
    5·2 answers
  • Which of the following did not occur during the collapse of the solar nebula?
    12·1 answer
  • In need of help!!!!!!
    7·1 answer
  • HELPPPP ME NEOWW please (: Which of these statements about Earth’s magnetic
    7·2 answers
  • Is my answer correct? Please i need to know
    13·2 answers
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!