Answer
784 $\frac{N}{m}$
Work Step by Step
The equation for spring constant is $\frac{N}{x}$. Using this formula, we must find gravitational force first. Using the equation for weight (m$\times$g), we find that the weight is 8kg $\times$ 9.8 $\frac{m}{s}$ =78.4N. Now that we have N, and m is found by the distance in meters the spring is compressed(10cm=.1m), we simply plug into the equation for spring constant. $\frac{78.4}{.1}$= 784 $\frac{n}{m}$