Let's rewrite Hook's law:
[tex]F=-kx[/tex]
where
F is the force
k is the spring's constant
x is the compression/elongation of the spring
Neglecting the sign (since we are not interested in the direction of the force), we can re-arrange the formula and use the data of the problem to find the spring constant:
[tex]k= \frac{F}{x}= \frac{4 N}{2 cm}=2 N/cm [/tex]
Therefore, the correct answer is B) 2 N/cm.
