C) An identical spring is pulled with a force or 75 N The elastie limit of the spring is 72N Suate and explain whether or not the spring will return to its original shape.

Spring cannot return to its original, since a part of its deformation is plastic, not elastic.

Explanation:

Physically speaking, stress is equal to the axial force divided by effective transversal area of spring. In addition, springs have usually a linear relationship between stress and strain in elastic region, since they are made of ductile materials. Axial force is directly proportional to axial stress, which is also directly proportional to axial strain.

Then, if force is greater than force associated with elastic limit of the spring, then spring cannot return to its original, since a part of its deformation is plastic, not elastic.

305.7

explanation:

density =m/v

density =917/3.00

density = 305.

approximately = 305.7

in four significant figures