A projectile of mass 0.874 kg is shot straight up with an initial speed of 29.0 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 7.70 m, determine the magnitude of the average force due to air resistance.
(a) Number ..... Units ....
(b) Number ..... Units ....
Answer *1: the tolerance is +/-1 in the 3rd significant digit
Answer *2: the tolerance is +/-1 in the 3rd significant digit
With no air friction, it should rise to an altitude H such that
M g H = (1/2) M Vo^2
H = Vo^2/(2g) = 42.9 m
If it rises to only 7.70 m, 82.05% of the initial kinetic energy is lost due to air friction. That is a lot.
The average friction force is energy lost (in Joules) divided by 7.70 meters