dane:
m = 2 kg
h = 50 m
szukane:
v_k = ?
t = ?
Energia całkowita nie ulegnie zmianie.
E_c₁ = E_c₂
E_c₁ = E_p₁ + E_k₁ = E_p₁ + 0 = E_p₁ = mgh
E_c₂ = E_p₂ + E_k₂ = 0 + E_k₂ = E_k₂ = mv²/2
mgh = mv²/2
gh = v²/2
v_k = √(2hg) = √(100 m * 9,81 m/s²) = √(981 m²/s²) ≈ 31, 32 m/s
h = at²/2
a = (v_k - v_p)/t = v_k/t
h = v_k * t/2
t = 2h/v_k = 100 m/31, 32 m/s ≈ 3,19 s
