physics
posted by guy on .
On Earth a rock falls an unknown vertical distance from a resting position and lands in a lake. If it takes the rock 2.5 seconds to fall, how high is the cliff that the rock fell from?

the formula for vertical distance is,
d = (v0)*t(1/2)g*t^2
where v0=initial velocity, t=time, and g=acceleration due to gravity, which is approximately 9.8 m/(s^2)
*now since this is freefall, v0 = 0 and the formula reduces to:
d = (1/2)g*t^2
d = (1/2)*9.8*(2.5^2)
then solve for d. units in m. (get its absolute value since it's distance) 
THANK YOU =0]