Im confused. I have algebra 1 and we are doing story problems. We have to use the equation h=-16t^2+vt+s to answer the following questions:

(a) A cat leaps from the ground into the air an initial vertical velocity of 11 feet per second. After how many seconds does the cat land on the ground?

(b) A pine cone falls from a branch that is 100 feet above the ground. After how many seconds does the pine cone land on the ground?

(c) A soccer ball is kicked upward from the ground with an initial velocity of 12 feet per second. After how many seconds does it land on the ground?

I'm really confused on how to set the problems up. Please explain. Also what is the -16t^2 in the equation that is used to solve these problems for? It doesn't have anything to do with the problems? Thank you!