if the stretch in a spring of force constant k is doubled:calculate
a)ratio of final to initial force in the spring
b)ratio of elastic energies in 2 cases
c)work done in changing the double stretch
1. for a given spring F=kx so F2/F1=kx2/kx1=2x/x=2
2. U=1/2kx2 so U1/U2=4x2/x2=4
3. as work done in stretching the spring is stored in the form of elastic potential energy so W= U2-U1=1/2k(4x2-x2)=3/2kx2