Hi guys! I need some help :) A projectile of mass 0.709 kg is shot straight up with an initial speed of 18.7 m/s. (a) How high would it go if there were no air resistance? (b) If the projectile rises to a maximum height of only 7.58 m, determine the magnitude of the average force due to air resistance. So I figured out how to do part a) by setting KE=PE and solving for h. I just don't know what to do to solve for part b. I have been trying to find the work and the plug the work into the W=FdCos (theta) equation, but I can't seem to get the right answer. THANKS!