Fun practice

1.  A rock is dropped from a 100-m high cliff.  How long does it take to fall the first 50-m, and the second 50-m?

2.  A  juggler usually tosses balls vertically to a height H.  To what height must they be tossed if they are to spend twice as much time in the air?

3.  Two objects are begin a free fall from rest from the same height, 1 second apart.  How long after the first object begins to fall are the 2 objects 10 m apart?

4.  A hot air balloon is ascending at a rate of 12 m/s and is  80-m above the ground when a package is dropped over the side.  How long does it take the package to hit the ground, and with what speed does it hit the ground?