Question on Dynamics. Finding the force

Question

A man of 75kg is standing in the basket of a hot-air balloon. The balloon is rising at 5ms-1 and 4s later it is descending at 3ms-1. Assuming constant acceleration, find the normal contact force of the man?

Answer 1

Find the acceleration of the balloon: (v-v₀)/t = (-3-5 m/s)/4s = -2 m/s²

Assuming that the man keeps his feet in contact with the balloon, he also accelerates at -2 m/s²

The free body diagram on the man indicates that F_N - F_Wt = ma where F_Wt = mg

Therefore F_N = ma + mg (a is negative)