Astone falls from a ledge and takes 8 seconds to the hit the ground. the stone has an original velocity of 0 m/s. how tall is the ledge?

Using equation of motion.

S = ut + (1/2)gt²

Where S = Height, t = time, g = acceleration due to gravity = 9.8 m/s²

time, t = 8 seconds 

Since it was dropped from height, initial velocity, u = 0

S = 0*t + (1/2)gt²

S = (1/2)gt²

S = (1/2)*9.8*8²  = 4.9 * 8 * 8 =  313.6

Therefore the ledge is 313.6 m tall.