Question

 

 

A spring suspending a 3-pound weight stretches to a length of 7 inches. The spring stretches 0.5 inches per pound of load.

What would the length of the spring be if 15 pounds were suspended?

Answer 1

The 3lb load stretches the spring 0.5"*3=1.5". So the string without load is 7-1.5=5.5" long.

A 15lb load stretches the spring by 15*0.5=7.5" plus the unstretched length=7.5+5.5=13".