Two different types of rubber are found to have the stress-strain curves shown below in the figure below. 

         

(i)  In which significant ways do these curves differ from the stress-strain curve of a metal wire.

(ii)  A heavy machine is to be installed in a factory.  To absorb vibrations of the machine, a block of rubber is placed between the machinery and the floor.  Which of the two rubbers A and B would you prefer to use for this purpose?  Why?

(iii)  Which of the two rubber materials would you choose for a car tyre?

 

Asked by Topperlearning User | 4th Jun, 2014, 01:23: PM

Expert Answer:

(i)  The curves differ as regards the following points :

(a)  The linear portions of the curves being smaller, Hooke's law is not obeyed even for small stress.

(b)  There is no permanent strain even for large stresses.

(c)  The elastic region is larger in the present curves.

(d)  During unloading, the same curve is not retraced in the present case.

(ii)  We should use rubber B to absorb vibrations of the machinery.  It is because of larger area of the curve that greater amount of vibrational energy can be dissipated.

(iii)  We should use rubber A for making car tyres.  Because the work done in case rubber A is lesser (lesser area of the curve), hence the car tyres of this rubber will not get excessively heated.

 

Answered by  | 4th Jun, 2014, 03:23: PM