a) la momentul t1 = 5s Ep1 = 100j mgh1 =100 h1 = Ep/(mg) = 100/10 = 10m
b) la momentul t2 = 10s Ep2 = 200j mgh2 = 200 ⇒ h2 = 20m
Δt = t2 - t1 = 5s Δh = h2 - h1 = 10m v = Δh/Δt = 10/5 = 2 m/s
c) P = L/Δt = G·Δh/Δt =1·10·10/5 = 20w
d) la inaltimea h = 20m E = Ep = mgh = 200j
la sol : E = Ec = mv² /2
mv² /2 = mgh v² = 2gh = 400 v = 20m/s
