- la inaltimea h: Ep = mgh Ec = 0 Et = Ep + Ec = mgh
- in cadere Ep se transforma in Ec , dar , Et ramane constanta;
- la inaltimea h1 : Ep = mgh1 Ec = m/2 ·v²
mgh1 + mv² /2 = mgh
g·v²/2g + v²/2 = gh
v² = gh v = √(9,8·5) = √49 = 7m/s
gh1 + 2·gh1 = gh 3h1 = h h1 = 5/3 m