Why are shock absorbers used in motor cycles and cars ?

When the vehicle moves over an un even road, it receives a jerk. So the vehicle receives the impulse force. To minimize this impact shock absorbers are used.
$\text{ Impulse }=\mathrm{F}\left(\mathrm{\Delta t}\right)\Rightarrow F\propto \frac{1}{\mathrm{\Delta t}}$
The shock absorbers increases the time of the jerk, there by reducing the impulsive force. This minimizes the damage to its vehicles.