At what initial speed should the body be thrown vertically down from a height of 9.8 m so that it falls in 0.5 s.

Initial data: H (height at which the body was located) = 9.8 m; t (duration of the fall of the body) = 0.5 s.

Constants: g (acceleration of gravity, acceleration of a body) = 9.8 m / s ^ 2.

The initial speed with which you need to throw the body, we express from the following formula:

H = V0 * t + g * t ^ 2/2; V0 * t = H – g * t ^ 2/2; V0 = (H – g * t ^ 2/2) / t.

Let’s perform the calculation:

V0 = (9.8 – 9.8 * 0.5 ^ 2/2) / 0.5 = 17.15 m / s.

Answer: The body must be thrown vertically downward with an initial speed of 17.15 m / s.