Two different types of rubbers are found to have the stress -strain curve of a metal wire .
(a) In which significant way do these curves differ from the stress-strain curve of a metal wire shown in Figure.
(b) A heavy machine is to be installed in a factory. To absorb vibrations of the machine, a block of you preferr to use for his purrpose ? Why?
(c ) Which of the two rubber materials A,B would you choose for a car tyre ?

Explanation

(a) Here Hooke.s law is not obeyed, as thegraphs are not straight at any region of the graph. During unloading, the strain lags behind stress. This is called elastic hysteresis. Both material show this.
(b) Rubber absorbs vibrations and converts it into heat. This can be done more efficiently by selecting that rubber which has a large area( shaded region) for the hysteresis loop. Hence rubber B can be used.
(c ) The rubber which has least area for the hysteresis loop must be used for a car tyre, so that least energy will be wasted in the form of heat, so rubber A can be used.