If you take a deep breath of air, you can float more easily in water because you have .
A. increased your weight
B. decreased your weight
C. increased your buoyant force
D. decreased your buoyant force

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)