3 B S c i e n t i f i c ® E x p e r i m e n t s
1
OBJ ECT IVE
Experimental investigation of the vector
addition of forces.
UE102030
Mechanic s / Force
Parallelogram of forces
SUMMARY
The vector addition of forces can be demonstrated in a clear and simple manner on the
force table. The point of action of three individual forces in equilibrium is exactly in the
middle of the table. Determine the magnitude of the individual forces from the suspen-
ded weights and, using a protractor, note the angle of each force vector (the direction of
each force). The result of the experiment can be evaluated analytically or represented as a
graph.
E XPERIMENT PROCEDURE
• Plotting the equilibrium of three
arbitrary forces on a graph
• Analytical investigation of the
point of equilibrium when forces
F
1
and
F
2
are symmetrical
Quantity Description
Number
1
Force Table
U52004
BAS IC PRINC IPLES
Forces are vectors and can therefore be added using the rules of vector addition. To
demonstrate the sum of two vectors on a graph, the point of origin of the second vec-
tor is placed on the final point of the first vector. The arrow from the point of origin of
the first vector to the final point of the second vector represents the resultant vector.
By completing the parallelogram (of which the two vector lines are sides), a diagonal
drawn from the original angle to the opposite corner represents the resultant vector
(also see Fig. 1).
required apparatus
