How to find the acceleration of gravity?

The free fall acceleration g can be found in two ways.

With a mathematical pendulum.
Take a metal ball and hang it from the suspension on a thread of length l. Tilt at a small angle from the equilibrium position and release. Using a stopwatch, measure the time of one complete oscillation, that is, find the oscillation period T.

The period of free oscillations of a mathematical pendulum is determined by the formula: T = 2 * P * √ (l / g).

By the formula g = 4 * P ^ 2 * l / T ^ 2 we find the acceleration of gravity g.

Take the body, raise it to a certain height h and release it. Using a stopwatch, measure the fall time of this body t.
The body will move with constant acceleration g without initial velocity.

The height of the fall h will be determined by the formula: h = g * t ^ 2/2.

By the formula g = 2 * h / t ^ 2 we find the acceleration of gravity g.