Răspuns:
suspendat de primul resort G=Fe1, mg=k1*Dl1
k1=mg/Dl1
suspendat de al doilea resort
k2=mg/Dl2
la legarea in paralel a resorturilor constanta elastica echivalenta este ke=k1+k2
adica mg/Dl=mg/Dl1+mg/Dl2
1/Dl=1/Dl1+1/Dl2
1/Dl=1/20+1/5
1/Dl=1/20+4/20
1/Dl=5/20
Dl=20/5=4 cm
Explicație: