A 2 m long friction bolt is pushed into a drill hole with a force F. The force is in equilibrium with the distributed load r (which has units of N/m) from the surrounding rock. Create a formula for the force F as a function of embedment length x. Determine the force at x = 1.5 m. (a) F is constant with r = 15 N/m (b) varies linearly with r = 25x + 5 N/m