What is an advantage of using oil instead of wind to generate electricity?

a. oil can be used when there is no wind

b. oil releases greenhouses gases when burned

c. oil produces no pollution

d. oil is nonrenewable

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)