- #1
schyuler2
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Homework Statement
A ball is thrown straight upward from the ground with a speed of 30 m/s. What is the average speed of the ball in the first 5 seconds?
Homework Equations
VBy2 = VAy2 + 2(ay) * dABy
VBy = VAy + ay * change in time
Average velocity = dABy / change in time
The Attempt at a Solution
VBy2 = VAy2 + 2(ay) * dABy
(0)2 = (30)2 + 2(9.8) * dABy
0 = 900 + 19.6 * daby
-900 = 19.6 *dABy
-45.9 = dABy
^but dABy can't be negative. what am i doing wrong?
also-- do i use "5 sec" for my time interval on the other equations? i cannot figure out what it means by "first 5 seconds." HELP