What is the displacement of a spring if it has a spring contstant of 10 n/m, and a force of 2.5 n is applied?

Will you chech and finish these for me, because i am stumped with them.

What does si stand for,when referring to a system of measurement

An air-filled capacitor is formed from two long conducting cylindrical shells that are coaxial and have radii of 26 mm and 103 mm. the electric potential of the inner conductor with respect to the outer conductor is - 700 v (k = 1/4πε 0 = 8.99 × 109 n · m2/c2) the energy stored in a 1.0-m length of this capacitor is closest to