WAEC Physics 2019 Paper

Concept:For a freely falling body, the kinetic energy gained is equal to the gravitational potential energy lost.Explanation:The body is released from rest, so its initial kinetic energy is zero.At a point $80 \, \text{m}$ from the point of release, the distance fallen is $h = 80 \, \text{m}$.Loss in potential energy is $\Delta P.E. = mgh$.Substitute $m = 2 \, \text{kg}$, $g = 10 \, \text{m/s}^2$, and $h = 80 \, \text{m}$.$K.E = mgh = 2 \times 10 \times 80 = 1600 \, \text{J}$.Thus, the kinetic energy of the body at that point is $1600 \, \text{J}$.Answer:A. $1600 \, \text{J}$