Aplicam legea de conservare a energiei intre punctul de lovire B si punctul in care bila se opreste C.Astfel Ec_B=Ep_C=>m₂u²/2=m₂gh=>u²=2gh
h=10 cm=0,1 m
u=√2gh=√2*10*0,1=√2=1,41 m/s
u=(m₁v₁+m₂v₂)/(m₁+m₂)<=>1,41=10⁻²v₁/(10⁻²+10)<=>1,41=10⁻²v₁/10,01=>v₁=10,01*1,41/10⁻²=1411,41 m/s