Mechanical Q: Find Air Resistance Force from .750kg Proj. at 18.0m/s

[dbtarz]

A projectile has a mass of .750kg and is shot straight up with an initial velocity of 18.0m/s. If the projectile rises to a max height of 11.8m, determine the magnitude of the average force due to air resistance. Can anyone help me with this?

 

[Kurdt]

What have you tried so far?