A box that has a weight of 40 N is hung from a spring. The spring constant of the spring is 400 N/m. How many centimeters will the spring stretch? 0.1 cm 1 cm 10 cm 100 cm

The mathematical relationship between force and extension for a spring is F = - kx, where F is the restoring force, k is the spring constant and x is the extension. If a box that weighs 40 N is hung from a spring of content 400 N/m, then the extension is equal to x = - F / k = - 400 / 40 = - 10 cm. The negative sign simply shows the extension and restoring force are in opposite directions. The answer is 10 cm.