Projectile Motion with air resistance -- need urgent help Consider a projectile fired vertically in a constant gravitational field. For the same inital velocities, compare the times required for the projectile to reach its maximum height (a) for zero resisting force and (b) for a resisting force proportional to the instantaneous velocity of the projectile. For a, I get t=-v0/a. For b, I have the equation F= m dv/dt=kmv-mg, which leads me to dv/dt=kv-g. Is this correct...If so, I can take it from here. If not what should it be?? What should my initial condition be to solve for the constant? Should it be v(t=0)=v0??? Thanks much!!!