Physics lab report 1 - Equilibrium of Forces Acting at a...

Equilibrium of Forces Acting at a Point
Phys 104L—Section 435
Lin Letian
September 13, 2006
Josh Kahn
Lab partner: Shanley Morgan
UNC Honor Pledge:
_______________________

Abstract
In this experiment, we investigated the hypothesis that forces exhibit additive
properties and also allowed extensive practice with the concept of uncertainty. Both parts
of the experiment challenged us to find an additional force vector that would cancel out
the two or three forces working in opposite directions. Weights were attached to strings
that pulled in varying directions against a small ring in the center of a force table. The
position of the ring versus the pin that it surrounded illustrated whether the system was in
translational equilibrium. Through graphical and numerical analysis, we determined the
sum of the forces that brought our system into equilibrium. Taking into account the
uncertainty of the measurement of force, the results supported the commonly accepted
theory that force vectors can be summed.
Discussion
The condition for static equilibrium is satisfied in both parts of the experiment.
Although the net force on the ring in part I of 0.033 N appears to disallow the ring from
being in equilibrium, the experimental uncertainty of 0.082 N permits us to discount this
force as negligible. The uncertainty, as a result of limited accuracy and precision of the
instruments, suggests that 0 net force is in the range of possible forces exerted on the
ring.