Atourist drops a rock from rest from a guard rail overlooking a valley. what is the velocity of the rock at 4.0 s? what is the displacement of the rock at 4s

At the end of 4.0 s the velocity of the rock is 39.24 m/s and its displacement from the point where it was dropped is 78.48 m.

The rock dropped from the guard rail is a freely falling body and is accelerated downwards under acceleration due to gravity.

To calculate the velocity after t=4.0 s, use the equation of motion,

Here, u is the rock's initial velocity, which is zero. It falls under acceleration due to gravity, hence a =g=9.81 m/s².

Therefore,

If it falls through a distance s, then, use the equation,

Therefore,

Thus, after 4.0 s, the rock has a downward velocity of 39.24 m/s and it would have traveled a distance of 78.48m.

does anyone know or what?