An object on another planet with g= 25 m/s^2 hits the ground in 5 s.
What is its final speed?

using the kinematic equation  V= Vo+ a t

Explanation:

I'm guessing that the object starts from "rest" and is allowed to fall to the planet and takes 5 seconds to hit the ground

V =25 * 5

V=125 m/s    .. pretty fast that's about 280 MPH  

a longitudinal wave moves energy that is to the direction of the wave’s movement. - true

powerful computers now, not then