Răspuns:
1. m=10kg
v=6m/s
Ec=mv^2/2=10*36=360:2=180J
2.Ec=200J
m=?
v=10m/s
200J=m*100/2
200J*2=m*100
400J=m*100
m=400/100
m=4kg
3.Ep=mgh
Ep=20*30
Ep=600J
4.Ec=9.6J
m=0.3kg
v=?
9.6J=0.3kg*v^2/2
9.6J*2=0.3kg*v^2
19.2=0.3kg*v^2
v^2=19.2/0.3
v^2=64
v=√64
v=8m/s
5.12.000J=m*2000m
m=6kg