A ball is thrown horizontally from the top of a 66 m building and lands 90 m from
the base of the building. Ignore air
resistance
a) How long is the ball in the air?
s
b) What must have been the initial
horizontal component of the velocity?
2
m/s
c) What is the vertical component of the
velocity just before the ball hits the
ground?
m/s
d) What is the velocity and angle of the
ball just before it hits the ground?
m/s
Degrees below x-axis

Explanation:

Doppler effect: It is the phenomenon in which there is relative motion between the source and the observer or the source and the listener. There is an apparent change in the frequency.

When the observer and the source are moving towards each other then the frequency increases.

When the observer and the source are moving away from each other then the frequency decreases.

The expression of the speed of the wave in terms of the frequency is as follows;

Here, v is the speed of the wave, f is the frequency of the wave and is the wavelength of the wave.

From the above relation, it can be concluded that speed of the sound is directly proportional to the frequency of the wave.

The magnitude of the Doppler shift increases when the velocity of the sound source is increased.