Answer:
a) v = 34.5 mph, b) v = 50 mph
Explanation:
The average speed is defined.
v = (x₂ -x₁) / (t₂ -t₁)
If the movement is with uniform speed we can also obtain the average speed, averaging the speeds with a time weight factor, if the time is equal for each speed
v = (v₁ + v₂) / 2
a) For the outward journey
v = (69.0 +0) / 2
v = 34.5 mph
b) For the return trip
v = (69.0 + 31.0) / 2
v = 50 mph
Answer:
The frequency the motorcyclist hears is 601.60 Hz
Explanation:
The Doppler effect is a physical phenomenon where an apparent change in wave frequency is presented by a sound source with respect to its observer.
The following expression is considered the general case of the Doppler effect:
Where:
f ’, f: Frequency perceived by the receiver and frequency emitted by the emitter respectively. Its unit of measurement in the International System (S.I.) is hertz (Hz), which is the inverse unit of the second (1 Hz = 1 s-1)
v: propagation speed of the wave in the medium. It is constant and depends on the characteristics of the medium. In this case, the speed of sound in air is considered to be 34o m / s
vR, vE: Receiver and emitter speed respectively. Your unit of measure in the S.I. is the m / s
±, ∓:
The + sign is used:
- In the numerator if the receiver approaches the sender
.
- In the denominator if the emitter moves away from the receiver
.
The sign - is used:
- In the numerator if the receiver moves away from the sender
.
- In the denominator if the emitter approaches the receiver.
In this case:
- f: 523 Hz:
- v= 340 m/s
- vR= 13.6 m/s
- vE= 32.6 m/s
-
The emitter approaches the receiver, so the + sign is used in the numerator and the - sign is used in the denominator.
Replacing:
Solving:
f' = 601.60 Hz
<u><em>
The frequency the motorcyclist hears is 601.60 Hz</em></u>
Pressure is a measure of force per unit area
Velocity of the plane relative to the air = +400.0 m/s
Velocity of the air relative to the ground = -35.0 m/s (negative because it's moving opposite to the eastward direction)
Velocity of the plane relative to the ground = (velocity of the plane relative to the air) + (velocity of the air relative to the ground) = 365.0 m/s to the east