Describe the forces acting on a skydiver over time, from the moment she jumps out of the plane until hitting the ground and the effect this has on her velocity. What happens when she opens her parachute?

When the skydiver first steps out of the plane, she accelerates downwards at a high rate. At first the resultant force on her is large since gravity pulls her down, but since she is moving slowly the force from air resistance is small. As she accelerates, the drag force increases until it is equal to the force of gravity. The two forces acting on the skydiver are now equal and opposite so she has reached her terminal velocity and moves at a constant speed. When she opens the parachute, the drag force becomes much larger than the gravitational force, and so the resultant force is upwards. The skydiver quickly decelerates before landing and coming to a stop.