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vodka [1.7K]
3 years ago
14

An avant-garde composer wants to use the Doppler effect in his new opera. As the soprano sings, he wants a large bat to fly towa

rd her from the back of the stage. The bat will be outfitted with a microphone to pick up the singer's voice and a loudspeaker to rebroadcast the sound toward the audience. The composer wants the sound the audience hears from the bat to be, in musical terms, one half-step higher in frequency than the note they are hearing from the singer. Two notes a half-step apart have a frequency ratio of 21/12 = 1.059. With what speed must the bat fly toward the singer?
Physics
1 answer:
Brilliant_brown [7]3 years ago
6 0

Answer:

18.94  m/s

Explanation:

The bat becomes the source of sound . Source is moving towards observer

apparent frequency = actual frequency x (V / V - V_s)

V is velocity of sound and V_s is velocity of source or bat.

apparent frequency / actual frequency = V / (V - V_s)

21 / 12 = 340 / (340 - V_s)

1.059(340 - V_s) = 340

340 x .059 = 1.059 V_s

V_s = 18.94  m/s

=

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I just don't know how to do the question (a) and (b)​
ozzi

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F=ma

we can observe that you have to apply a non-zero net force to an object in order to make it accelerate. In fact, if the net force is zero you have

0=ma \iff a=0

Since we're assuming n\neq 0

Now, if the 12N force is applied, the object moves with a constant speed. A constant speed means no acceleration, since by definition the acceleration is a change in speed.

If this sounds counterintuitive to you (why I'm applying a force but I have to acceleration?) think of when we drive a car: even if you want to keep your speed constant, you still have to use the gas pedal, just enough so that the push of the motor balances exactly the road/wheels friction. If you give less gas, the friction becomes stronger, and the car slows down. If you give more gas, the motor push becomes stronger, and the car accelerates.

Back to your exercise: constant speed means to acceleration, so the net force must be zero. This implies that the friction force is exactly 12N.

If the force is increased to 18N, there will be a net force of 6N pushing the object, causing it to accelerate. Using again the same equation of before, and plugging the 3kg mass in the equation, we have

F=ma \iff 6=3a \iff a=2

So, the object moves with constant acceleration and initial speed of 10m/s for 0.2 seconds. It's final speed will be

v = v_0+at = 10+2\cdot 0.2 = 10.4

5 0
3 years ago
A student weighing 700 N climbs at constant speed to the top of an 8 m vertical rope in 10 s. The average power expended by the
nasty-shy [4]

Answer:

The average power the student expended to overcome gravity is 560W, Watts is a units of work it is Joules /time or kg*m^{2}/ s^{3}

Explanation:

Weight = 700N

F= m*g*h \\m*g= 700N\\F= 700N*h\\F=700N*8m\\F= 5600 N*m \\F=5600 J

The power is the work in (Joules) or (N*m) in a determinate time (s) to get Watts (W) units for work

Work= \frac{5600 J}{10s} = \frac{5600 \frac{kg*m^{2} }{s^{2} } }{10 s}  \\Work= 560\frac{kg*m^{2} }{s^{3} } \\Work =560 W

3 0
3 years ago
What is it called when something doesn’t flow easy
LUCKY_DIMON [66]

Answer:

That something is called having a high viscosity.

Explanation:

The measure expressing a "resistance to flow" is called viscosity. Viscosity relates to  internal friction forces in a fluid causing it to flow with more or less difficulty. Highly viscous stuff is perceived "thick" or "sticky."

7 0
3 years ago
A car is moving from rest and the velocity increases to 30 m/s in 4 seconds. Calculate its acceleration.
vaieri [72.5K]

Answer:

7.5 m/s²

Explanation:

Given:

v₀ = 0 m/s

v = 30 m/s

t = 4 s

Find: a

v = at + v₀

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a = 7.5 m/s²

8 0
3 years ago
What is the total resistance in the circuit? (include unit in answer - ohms)
solmaris [256]

Answer:60 ohms

Explanation:

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R3=15 ohms

Let the total resistance be R

R=R1 + R2 + R3

R=30 + 15 +15

R=60

Total resistance is 60 ohms

4 0
3 years ago
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