In: Physics
Energy can be stored in an elastic band by stretching
it.
Let x be the distance over which the band is stretched.
If the force which the band exerts to restore itself to its
original
shape is given by F = ax + bx2
, where a and b are constants,
find work done in stretching the band from x=0 to x=L.
(a) aL+ bL2
(b) (aL2+ bL3)/2
(c) aL2/2+ bL3/3
(d) (aL2/2+ bL3/3)/2.
Infinitesimal Work  
done to stretch the rubber band by infinitesimal
length  
under the application of force 
 will be given as,

Integrating above equation over variable from 
 to 
, we will get, the net work done 
 in stretching the rubber band by length 
 as,



work done to stretch the rubber band by length of 
,
,

Using given expression for force that is 
 in above integral we will get,


Solving the integrals we get,



So, we get the work done in stretching rubber band from
 as,
