Answer:
V0=27.4 m/s; t=0.8 s
Explanation:
Final position y=37.0 m, time = 2.3 s; Initial position is set to be zero. We calculate the initial speed with the kinematics equation:
We solve for initial speed

Now, using the same expression we estimated time to first reach 18.5 m :
Second order equation with solutions
t1=0.8 s and t2=4.8 s
The first time corresponds to the first reach.
Answer:
The minimum riding speed relative to the whistle (stationary) to be able to hear the sound at 21.0 kHz frequency is 15.7 m/s
Explanation:
The Doppler shift equation is given as follows;

Where:
f' = Required observed frequency = 20.0 kHz
f = Real frequency = 21.0 kHz
v = Sound wave velocity = 330 m/s
= Observer velocity = X m/s
= Source velocity = 0 m/s (Assuming the source is stationary)
Which gives;

330 -
= (20/21)*330
= 330 - (20/21)*330 = 15.7 m/s
The minimum riding speed relative to the whistle (stationary) to be able to hear the sound at 21.0 kHz frequency = 15.7 m/s.
Answer:
3100 m/s
Explanation:
The relationship between frequency and wavelength of a wave is given by the wave equation:

where
v is the speed of the wave
f is its frequency
is the wavelength
For the wave in this problem,
f = 15,500 Hz

Therefore, the wave speed is
