an object of mass 30 kg is falling in air (a=9.8m/s^2) and experiences a force due to air resistance of 50 newtons. Determine the net force acting on the object and calculate the acceleration of the object

Ahot-air balloon takes off from the ground traveling vertically with a constant upward acceleration of magnitude g/4. after time interval δt, a crew member releases a ballast sandbag from the basket attached to the balloon. how many seconds does it take the sandbag to reach the ground? (express your answer in terms of δt)