Part 1)
here Julie is running at speed 5 m/s
So here two balls are thrown at speed 10 m/s towards Julie with respect to her friend standing on the ground.
So here this all speed is real speed of all.
Now as per Anita (let say she is one of her friend standing on ground) the speed of two balls will be same as the given speed as she is observing from ground or stationary frame
As per the frame of Julie
speed of ball 1

towards her in same side
speed of ball 2

towards her from opposite side
Part b)
Now in this case the speed of two balls is given with respect to Julie
so we can say
for ball 1


so in ground frame speed of ball 1 is

Similarly for ball 2


So speed in ground frame of ball 2 is

so its 5 m/s from opposite side
Technically friction is acting on the car because it is still rubbing against the street and gravity is pulling the car down preventing it from floating??? lol
Answer:
The same in both the regions of constructive interference and the regions of destructive interference.
Explanation:
Interference is a phenomenon which occurs when two waves meet while moving along the same medium . The amplitude formed as a result of the interference could be greater, lower, or the same amplitude.
Constructive and destructive interference result from the interaction of waves that are correlated or coherent with each other. This is because arose from the same source or they have the same or nearly the same frequency.
The waves being coherent, arising from the same source and having the same frequency explains why it’s the same in both the regions of constructive interference and the regions of destructive interference.