A block is suspended from a vertical spring and comes to rest at a point where the spring is stretched beyond its natural length. Which of the following best explains why this resting position is not at the spring’s natural length?
(a) Because the spring must stretch until its elastic potential energy equals the gravitational potential energy lost by the block.
(b) Because the downward weight of the block must be balanced by an upward spring force, so the spring must be stretched at equilibrium.
(c) Because the mass of the spring effectively adds to the block’s mass, shifting the system’s center of mass downward and lowering the resting point.
(d) Because air resistance causes the block to come to rest at a lower point than the spring’s natural length.