Jane is riding in a hot air balloon that is rising vertically at a
constant speed of 3 m/s over a lake. She drops a rock from the balloon
when the distance from the rock to the water is 50 m. Use g=10
m/s², and let up be the positive direction. What is the
initial velocity of the rock?

1. 3 m/s
2. -3 m/s
3. 0
4. Cannot be determined.
5. None of the above.