posted by joshua .
A projectile of mass 1.450 kg is shot straight up with an initial speed of 20.0 m/s.
(a) How high would it go if there were no air friction?
(b) If the projectile rises to a maximum height of only 13.9 m, determine the magnitude of the average force due to air resistance.
The initial KEnergy is 1/2 m v^2
The PEnergy at to top must be equal to the initial KEnergy.
mgh=1/2 mv^2 solve for h. Notice m divides out.
b) forceresistance*13.9=1/2 m v^2
solve for the force.
bob's formula for B) is wrong...
Should be mgh-forceresistance = 1/2 m Vi^2