A paraglider is flying horizontally at a constant speed. Assume that only two forces act on it in the vertical direction, its weight and a vertical lift force exerted on its wings by the air. The lift force has a magnitude of 1900 N. For both questions, take the upward direction to be the +y direction.

Question

A paraglider is flying horizontally at a constant speed. Assume that only two forces act on it in the vertical direction, its weight and a vertical lift force exerted on its wings by the air. The lift force has a magnitude of 1900 N. For both questions, take the upward direction to be the +y direction. 
If the lift force should suddenly decrease to 1000 N, what would be the vertical acceleration of the glider

drwls · Accepted Answer

1900 N must be the weight, since it flies horizontally with that lift force. The mass must be 1900 N/g = 193.9 kg

The presumably includes the weight of the person flying the paraglider.

With a lift force of 1000 N, there is a net downward force of 900 N. The acceleration would be
F/m = 900 N/(1900 N/g) = (9/19)*g
= 4.64 m/s^2