Since, F = k . ∆x
Therefore, k = F / ∆x = 250 / 0.2 = 1250 N/m
(ps: convert 20 cm into 0.2 m)
Answer:
0.384c
Explanation:
To find the speed of the pursuit ship relative to the cruiser you use the following relativistic equation:

u': relative speed
u: speed of the pursuit ship = 0.8c
v: speed of the cruiser = 0.6c
c: speed of light
You replace the values of the parameters to obtain u':

Hence, the relative speed is 0.384c
High amplitude sound would be music, radio, or earthquakes.
Low amplitude sound would be a breeze or wind.