the first ounce of postage charges for sending letters to country x is $0.79. each additional ounce is $0.55. how much is the postage for a letter weighing 8 ounces?

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)