The discussion focuses on calculating the initial speed of a vertically thrown ball that reaches a height of 15 meters and takes 3 seconds to hit the ground. The relevant equations used are d = v_initial * t - 0.5 * g * t^2 and v = v_initial + g * t, where g represents the acceleration due to gravity (approximately 9.81 m/s²). By applying these formulas, the initial speed can be determined, and the time taken to reach 15 meters again can also be calculated using the properties of quadratic equations.
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Justas said:Homework Statement
Height - 15m
Time when ball hits the ground after upward throw 3 s.
I have been trying to find intitial speed with these formulas :
d=v_initial*t-0.5*g*t^2
and
v=v_initial+g*t
Please help to understand how to find initial speed and after what time the ball is at 15m height again.