Which of the following statements best describes the characteristic of the restoring force in the spring-mass system described in the introduction?
the restoring force is constant.
the restoring force is directly proportional to the displacement of the block.
the restoring force is proportional to the mass of the block.
the restoring force is maximum when the block is in the equilibrium position.

The restoring force is directly proportional to the displacement of the block

Explanation:

For a simple spring-mass system, the restoring force is given by Hooke's Law, which states that

where

F is the restoring force

k is the spring constant

x is the displacement of the block with respect to the equilibrium position of the spring (it corresponds to the compression/stretching of the spring)

Note that the force has a negative sign, since its direction is opposite to that of the displacement (because it is a restoring force, so it tends to "restore" the equilibrium condition)

From the equation, we see that the restoring force F is directly proportional to the displacement of the block, x.