At the start of the fall, the total enery that the object has is potential energy. Just before the object hits the ground, all the energy is converted to kinetic energy. The work done by air resistance is the difference in both energy.
From the information given,
mass, m = 0.005kg
height, h = 11.5
speed, v = 6m/s
We would calculate the kinetic energy by applying the formula
Kinetic energy = 1/2mv^2 = 1/2 x 0.005 x 6^2 = 0.09J
We would calculate the potential energy by applying the formula
Potential energy = mgh = 0.005 x 9.81 x 11.5 = 0.564 J
Work done by air resistance = 0.564 - 0.09
Work done by air resistance = 0.474 J
