The body, thrown vertically upward, fell to the ground after 3.0 seconds. How fast was the body thrown?
| April 5, 2021 | education
t = 3 s.
g = 9.8 m / s ^ 2.
V0 -?
The flight time of the body t will be the sum of t1 – the time of lifting the body to the maximum height and t2 – the time of the body falling from the maximum height to the ground: t = t1 + t2.
Only gravity acts on the body, so it will move up and down with the acceleration of gravity g.
t1 = (V0 – V) / g.
At the maximum height, the body will stop, its final velocity V = 0 m / s.
t1 = V0 / g.
The fall time of the body will be the same as the rise time, because all conditions are the same.
t2 = V0 / g.
t = V0 / g + V0 / g = 2 * V0 / g.
V0 = g * t / 2.
V0 = 9.8 m / s ^ 2 * 3 s / 2 = 14.7 m / s = 15 m / s.
Answer: the speed of throwing a stone is V0 = 15 m / s.
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