Answer the following questions on the basic statement of the principle that underlies the addition of small restoring forces:
a. (i) Define the principle of superposition as it applies to mechanical oscillations.
b. (ii) State any two essential conditions that must be satisfied for this principle to hold for a mass–spring system.
c. (iii) Give two everyday situations (one from laboratories and one from daily life) where the superposition of small restoring forces can be observed in practice.