Answer:
The velocity of the police car is, v = 17.798 m/s
Explanation:
Given data,
The actual frequency of the siren, f = 2010 Hz
The observed frequency of siren is, f' = 2120 Hz
The velocity of the observer, v' = 0 m/s
The velocity of the source, v = ?
The formula for Doppler effect,

Where,
V - velocity of sound waves in air.

Substituting the given values,

v = 17.798 m/s
Hence, the velocity of the police car is, v = 17.798 m/s
Answer:
yes
Explanation:
The plants use water (H2O) from the soil and carbon dioxide (CO2) from the air and recombine them to form carbohydrates (CH2O) and oxygen (O2).
Voltage = (current) x (resistance).
The current through the 60 ohms resistor is 0.10 A.
V = (0.10 A) x (60 ohms)
V = 6 volts
Most of the information's required are already given in the question. Based on those information's the answer can be easily deduced.
Wavelength of the sound wave = 0.450 meters
Speed of the sound wave = 330 meters per second
We already know
v=f<span>λ
</span>330 = f * 0.450
f = 330/0.450
= 733.33 hertz
So the frequency of the wave is 733.33 hertz
Answer: sum of forces is zero
Explanation: acording to the newton first law you can say that the sum of the forces acting over the object is zero no matter the direction of movement
good luck
mario