If you throw a super ball at 30 mph at a truck coming towards you at 30 mph, how fast does the ball

1
If you throw a super ball at 30 mph at a truck
coming towards you at 30 mph, how fast does the
ball come back assuming an elastic collision?
(green) 30 mph (red) 60 mph (orange) 0 mph (pink)
90 mph
2
You are holding a rope with a pulse traveling 10
m/s on it. How much harder do you have to pull
to get the pulse moving 20 m/s?
(green) the same (orange) twice as hard (pink)
half as hard (red) 4 x as hard
3
Given the values for density and compressibility
of water, what temperature has the highest
velocity?
T Compressibility density C x 10-10
m2/N g/ml
0 5.01 0.99987 10 4.78
0.99973 20 4.58 0.99823
30 4.46 0.99567
4
Which of the following is correct assuming that
the tension is the same throughout the entire
rope?