a uniform metal rod of length 80cm is suspended by a string at a point 22cm from the end. When a weight of 15N hangs from a point 13cm from the end, the rod balances in a horizontal position as shown in the diagram. How far from the string is the point where the weight of the metal rod acts

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)