Solve the all parts of given question:
Question: During liftoff, a hot-air balloon accelerates upward at a rate of 3.5m/s2. The balloonist drops an object over the side of the gondola when the speed is 15 m/s.
Part I: What is the magnitude of the object's acceleration after it is released (relative to the ground)?
Part II: What is the direction of the object's acceleration after it is released (relative to the ground)?
Part III: How long does it take to hit the ground?
Please show steps to find the magnitude of the object's acceleration after it is released.