Odpowiedzi

2009-12-22T19:00:03+01:00
Skorzystaj ze wzoru v₁² = v₀² + 2as.

v₀ = 400 m/s
v₁ = 0
s = 40cm = 0,4m

a = (v₁²-v₀²)/2s = (0²-160 000m²/s²)/0,8m = -200 000m/s²
2009-12-22T19:04:22+01:00
V = 400 m/s
s = 0,4 m
Ek = W
(m * v^2) / 2 = F * s
F = (m * v^2) / (2 * s)
a = F / m
a = (v^2) / (2 * s)
a = 400^2 / (2 * 0,4)
a = 200 000 m/s^2
v = a * t
t = v / a
t = 400 / 200 000 = 0,002 s