A stone is thrown vertically upward with velocity of 5 m/s,at the same time a stone is dropped from the height of 100 m,when will thy meeet each other?
5t - 4.9t^2 = 100 - 4.9t^2
t = 20
How can this be? The falling rock will hit the ground in 4.5 seconds. What it means is that the rock that was thrown upward will have fallen back to the ground (in 1.02 seconds) long before the falling rock arrives.
The only way this makes any sense is if the rock was thrown upward from the edge of a cliff, and both rocks could be in the air for 20 seconds.