A stone is dropped from a certain height. What will be the velocity of the stone after 8 seconds from the start of its fall if it never gets to touch the ground? What will the distance the stone traveled in that time?


g = 9.8 m/s2
t = 8 s

By applying the formula of velocity in free fall, we get that:

v=-g·t v = -9.8 m/s2 · 8 s  v= -78.4 m/s

To find out the distance traveled, we must calculate the displacement of the stone (Δy). This displacement is calculated by subtracting the position after 8 second (y8) from the position at the time 0 (y0). If we develop the equations of the position in both cases:

Δy = y8-y0 =H-12·g·t82 - H-12·g·t02 Δy =H-12·g·82 - H-12·g·82 Δy =H-12·9.8·82 -H Δy = 313.6 m

Formulas worksheet

These are the main formulas that you must know to solve this exercise. If you are not clear about their meaning, we recommend you to check the theory in the corresponding sections. Furthermore, you will find in them, under the Formulas tab, the codes that will allow you to integrate these equations in external programs like Word or Mathematica.

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