Answer:
f'=5.58kHz
Explanation:
This is an example of the Doppler effect, the formula is:

Where f is the actual frequency,
is the observed frequency,
is the velocity of the sound waves,
the velocity of the observer (which is negative if the observer is moving away from the source) and
the velocity of the source (which is negative if is moving towards the observer). For this problem:


Answer:
The Acceleration will increase
Explanation:
Newton's Second Law of motion: It states that the rate of change of momentum is directly proportional to the applied force and takes places along the direction of the force.
It can be expressed mathematically as,
F ∝ m(v-u)/t
Where (v-u)/t = a
F = kma.
F = force, m = mass of the body, a = acceleration, k = constant of proportionality which tend to unity for a unit force, a unit mass, and a unit acceleration.
Therefore,
F = ma.
From the equation above,
If the net force acting on a body increase, while the mass of the body remains constant, the acceleration will also increase.
<h2>Hello!</h2>
The answer is: 19.59 m
<h2>Why?</h2>
Since there is no information about the launch type, we can assume that the ball is thrown vertically upward.
When the ball reaches the maximum height, just at that moment, the velocity turns to 0, and after that moment, the ball starts falling, so:
We will use the following formula:

Where:
Vf= Final velocity = 0
Vi= Initial velocity = 
g = Gravity Acceleration = 
s = Traveled distance

Have a nice day!