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May 5, 2016

# Homework Help: science equation

Posted by Alli on Monday, December 5, 2011 at 10:41am.

I don't think I have enough information to answer this question but my teacher says i do. The question is, If I drop a ball off of the AUL building and it take 8 seconds to hit the ground what is the velocity of the ball? I know that v=d/t so I have v=d/8 so there is nothing else I can do. The next question is, How high is the AUL building in the last problem? Please help and thank you.
• science equation - MathMate, Monday, December 5, 2011 at 4:43pm

You have enough information, but not enough equations.

A free-falling object starting from rest accelerates (assuming no air resistance) and the distance from the starting point is given by:
x=-(1/2)gt²
where
x = distance from starting point, positive upwards
g = acceleration due to gravity, 32.2 ft/s², or 9.81 m/s², depending on the unit you use.
t = elapsed time in seconds since the beginning of the free fall.

For the first part, the velocity, v, after time t is given by:
v = -gt
again velocity is positive upwards.