Introduction to SAT II Physics - FreeExamPapers

of the spring due to the gravitational pull exerted on the mass. The equilibrium position is the
point where the net force acting on the mass is zero; in other words, the point where the upward
restoring force of the spring is equal to the downward gravitational force of the mass.
Combining the restoring force, F = –kh, and the gravitational force, F = mg, we can solve for h:
Since m is in the numerator and k in the denominator of the fraction, the mass displaces itself more
if it has a large weight and is suspended from a lax spring, as intuition suggests.
A Vertical Spring in Motion
If the spring is then stretched a distance d, where d < h, it will oscillate between
and .
Throughout the motion of the mass, the force of gravity is constant and downward. The restoring
force of the spring is always upward, because even at
the mass is below the spring’s initial
equilibrium position of x = 0. Note that if d were greater than h,
would be above x = 0, and
the restoring force would act in the downward direction until the mass descended once more
below x = 0.
According to Hooke’s Law, the restoring force decreases in magnitude as the spring is
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