• Created by: roopa
  • Created on: 27-04-15 10:27

Gravitational Potential Energy

The work done by an object by a force is

W = F x d


F = m x a


W = m x a x d

If the object is in free fall, then a = g and the distance is its height, d = h.

Thus the work done by gravity on the object (GPE) is

W = = GPE =  m g h

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Terminal Velocity

When a skydiver jumps out of a plane we consider the forces in 3 stages:

Immediately after jumping: There is zero drag, the only force acting is the weight and the acceleration is a = g = 9.81m/s^2

Before Terminal velocity is reached: The drag force increases and so the net force decreases  this means that a < g

At Terminal velocitydrag = weight and the acceleration is zero. Falling at constant speed.

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