Answer:
Speed of the soccer ball with respect to ground is ZERO
Explanation:
As we know that truck is moving with speed 20 mph
Now a soccer ball is shoot from truck with respect to the motion of truck in opposite direction
The relative speed of the soccer ball is

now we know that

so we have

so we have

For number one she is going to observe the contraction of the ballon
For number two she is going to observe the expansion of the ballon
Answer: A = 0.02 m²
Explanation: Solution:
Pressure is expressed in the formula:
P = F / A where F = mg
= mg /A
= 50 kg ( 9.8 m/s²) / 25000 Pa
= 0.02 m²
Energy of wave depends on its amplitude and it is given as

here k = constant
A = amplitude
so energy will increase or decrease depends on the amplitude of the wave
So here if we need to check which wave has lower energy then we need to compare the amplitude.
If the amplitude is less then energy must be less
So please check in the figure that which wave out of A and B has lesser amplitude to find out the wave of lesser energy