(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

A guy on the top of a 25m building throws a ball upwards with a initial vel of 12 m/s. A guy 31 m from the building catches it at the bottom of the building. What must be the average speed of the guy to catch it at the bottom.

2. Relevant equations

Using the Kinematics equations, and using acceleration = -9.80 m/s^2 and v= 0, I find the time up to be 1.22s. Then I find the distance up as 7.35m. Then I find the time it takes to fall down by adding 7.35 to 25 m, using initial velo as 0, and acceleration. But I get a negative on one side in this equation, x = vint(t) + (1/2)(a)(t^2). What am i doing wrong?

I know once I get this time I add it to 1.22s. Then I believe I use v=d/t and plug in 31m for distance and the total time.

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# Homework Help: Free-Falling Body Question

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