Explanation:
According to the given situation,
Change in kinetic energy = work done by all the forces
So, Change in kinetic energy = work done by gravitational force + work done by air resistance
[tex]mgh - F_{a}h = \frac{1}{2}m(v^{2} - 0^{2})[/tex]
Initial velocity of the rock will be zero. Since, the gravitational force is in the downwards direction hence, it will be positive. And, force due to air resistance is negative as it is in the upward direction.
Hence, putting the given values into the above formula as follows.
[tex]mgh - F_{a}h = \frac{1}{2}m(v^{2} - 0^{2})[/tex]
[tex]10 \times 9.8 \times 60 = \frac{1}{2} \times mv^{2}[/tex]
K.E = 4086 J
Thus, we can conclude that the K.E at the bottom of the fall is 4086 J.
