Physics 201 Lab: Centripetal Force
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Objectives
The main objectives for this laboratory exercise are to learn more about circular motion,
to study centripetal force, and to solve force equations
Method
The centripetal force on a stopper will be calculated by hanging a mass from a string and
swinging a stopper to balance out the forces.
Theory
If a mass follows a circular path, it is acted on by a centripetal (“center-seeking”) force.
In the case of the rubber stopper, the tension in the string causes the rubber stopper to
follow the circular path. If the rubber stopper is spinning in a circular path at constant
velocity then:
From Newton’s Second Law, Σ F = ma = 0 =T – mH g, since T causes the stopper to
move in a circular path then, FC = mSv2 /r = mHg
where T is the tension in the string, mH is the hanging mass, mS is the stopper mass, g is
the acceleration due to gravity, r is the radius of the circular path, and Fc is the
centripetal force.
