Answer:
b) 472HZ, 408HZ
Explanation:
To find the frequencies perceived when the bus approaches and the train departs, you use the Doppler's effect formula for both cases:

fo: frequency of the source = 440Hz
vs: speed of sound = 343m/s
vo: speed of the observer = 0m/s (at rest)
v: sped of the train
f: frequency perceived when the train leaves us.
f': frequency when the train is getTing closer.
Thus, by doing f and f' the subjects of the formulas and replacing the values of v, vo, vs and fo you obtain:

hence, the frequencies for before and after tha train has past are
b) 472HZ, 408HZ
Answer:
Hey!
Your answer should be D!
Explanation:
In a transformer Np / Ns is called the voltage ratio. If Ns is less than Np then Vs is less than Vp. This is called a step-down transformer as the voltage is reduced.
(source from google.com!)
Answer:
the answer is a time your welcome
The force of the racket affects the ball's motion because it changes the momentum of the ball.
<h3>Impulse received by the ball</h3>
The impulse received by the ball through the racket affects the motion because it changes the momentum of the ball.
The ball which is initially at rest, will gain momentum after been hit with the racket.
J = ΔP = Ft
where;
- J is the impulse received by the ball
- ΔP is change in momentum of the ball
- F is the applied force
- t is the time of action
Thus, the force of the racket affects the ball's motion because it changes the momentum of the ball.
Learn more about impulse here: brainly.com/question/25700778