One end of an ideal spring is connected with a smooth block with the other end with rear wall of driving cabin of a truck as shown in figure. Initially, the system is at rest. If truck starts to accelerate with a constant acceleration ‘a’ , then the block (relative to truck ):
In reference frame fixed to the accelerating truck, we may consider the block as shown in figure. A pseudo force F = m.a is acting on the block towards left. Since magnitude of the force is constant, therefore, maximum elongation of the spring will be equal to .
But for equilibrium, elongation of this spring should be equal to . It means block will start to perform oscillations and the amplitude of oscillations will be