A hot-air balloon consists of a basket, one passenger, and some cargo. Let the total mass be M. Even though there is an upward lift force on the balloon, the balloon is initially accelerating downward at a rate of g/3.
Draw a free-body diagram for the descending balloon.
Find the upward lift force in terms of the initial total weight Mg?
The passenger notices that he is heading straight for a waterfall and decides he needs to go up. What fraction of the total weight must he drop overboard so that the balloon accelerates upward at a rate of g/2 ? Assume that the upward lift force remains the same.