alungirea=forta * constanta elastica
constanta elastica=alungirea1/forta1=alungirea1/(masa1 *g)
In cazul alungirii de 4,5 cm
constanta elastica=alungirea2/forta2=alungirea2/(masa2 *g)
Deci alungirea1/(masa1 *g)=alungirea2/(masa2 *g)
masa2 *g=(masa1 *g)*alungirea2/ alungirea1
masa2=masa1* alungirea2/alungirea1
=> masa2 = 2*4,5/2=4,5 kg