dane:
m = 20 kg
s = h = 10 m
a = 5 m/s2
g = 10 m/s2
szukane:
W = ?
a)
W = Ep = mgh
W = m x g x h
W = 20kg x 10m/s2 x 10m = 2000 kg*m2/s2 = 2000 J
W = 2 kJ
========
b)
W = Fw x h
Fw = Fg + F
Fg = mg
F = ma
F = mg + ma = m(g+a)
W = m(g+a)h
W = 20kg x(10+5)m/s2 x 10m = 3000 kg*m2/s2 = 3000 J
W = 3 kJ
========
