1. A spring is an example of an elastic object - when stretched; it exerts a restoring force which tends to bring it back to its original length or equilibrium position.
This restoring force is proportional to the amount of stretch, as described by Hooke's Law:
Hooke's Law
The minus sign indicates F is a restoring force – it is directed to restore the mass to its equilibrium position.
The force constant k is equal to the slope of the Force vs. Stretch graph. Stiffer springs yield graphs with greater slopes.
kA > kB

2. Stretching an Ideal SpringF x F x kx
Work = Fx
Ws =

3. Work done by a spring V= ? m m k x
A helical spring is 50 cm long when a load of 80 N is hung from it and 52 cm when the load is changed to 82 N. Find its spring constant.
A certain spring that obeys Hooke's Law stretches 30 cm when a load of 0.35 N is added to it.  How much energy is stored in the spring when it is compressed 5.0 cm?
Work done by a spring
V= ? m m k x