The energy of an object of mass \(m\) associated with its motion is called kinetic energy \(K\), and varies as the mass of the object and the square of its speed \(v\):
[MATH]K=\frac{1}{2}mv^2[/MATH]
The speed of a falling object, at least in a mathematical model will depend on the details of that model, such as how drag varies with speed, and on the coefficient of drag which largely depends on the geometry of the object.
The point at which the impact with the ground becomes lethal will vary from person to person. A very massive person might find an impact resulting from a fall from a certain height lethal, whereas a lighter person might survive.
