When 2 forces act in the same direction the add together.
Answer
Hi,
The forces are; weight (gravity), Normal/centripetal force and friction. Force due to gravity is constant where as friction and centripetal are not.
Explanation
Weight is constant, given by the force of gravity on the object. The centripetal force is a function of the angles occurring between the velocity vector and the weight vector that is at right angle with the perpendicular line drawn from the surface. Friction is a function of the centripetal force thus it also varies.
Hope this helps!
As the plane falls the parabolic path remains directly below as the plane continues to fly over. This give more of an overview. When the package falls vertical acceleration happens as there is a vertical velocity as the package falls form high above. The downwards motion of gravity acts on the package if the approximated projectile motion ignoring air resistance.