Roger N. answered 05/26/20
. BE in Civil Engineering . Senior Structural/Civil Engineer
Solution:
With two springs connected in parallel, the following formula applies:
Keq = K1 + K2 , where K1 and K2 are the individual stiffness of each of the springs
Keq = The equivalent stiffness of both the springs connected in parallel
Knowing that F = Keq y , where y is the elongation given as 0.02 m
F = mg = Keq y , (500 g )(kg/1000 g) ( 9.81 m/s2) = Keq ( 0.02 m) , and
4.91 N = Keq ( 0.02m ), Keq = 245.5 N/m,
Knowing that the springs elongate the same distance, then they must have the same stiffness as they share the load, K1 = K2 = K
Keq = K1+K2 = 2K , 245.5 N/m = 2 ( K), K = 122.8 N/m