(a) The spring constant is 500 N/m.
(b) The extension of the spring when 25 N force is applied is 0.05 m.
(c) The applied force to cause an extension of 5 mm is 2.5 N.
The given parameters:
- Applied force, F = 10 N
- Extension of the spring, x = 20 mm
The spring constant is calculated as follows;

The extension of the spring when 25 N force is applied is calculated as follows;

The applied force to cause an extension of 5 mm is calculated as follows;

Learn more about Hook's law here: brainly.com/question/12253978
Answer:
velocity =displacement/time
and speed =distance/time
24-15=9 m/s slower in 12 seconds. So 9/12 m/s² slower. Therefore the acceleration is -0,75 m/s²