PHY122 Labs (Bennett & JCHS)
1
09/18/06
PHY 122 LAB : Vectors and Statics.
Introduction
Statics is concerned with the application of Newton' laws to things which don’t
accelerate. Examples include the design of bridges, elasticity (forces within
deformed material) and the forces which act at the junctions
between stationary rods
or strings. Then Newton's law
Σ
F = ma becomes
Σ
F=0.
It forms the basis for the
design of static structures such as cranes and buildings. In this lab, we will deal with
vectors in 2 dimensions. First, we will balance forces on a force table and thereby
see how to add vectors. Then we will do a statics problem involving torques. This is
vital knowledge for architects and engineers. For example, in aircraft design, you
want the lightest material which is strong enough. Statics tells you the forces which
arise when the aircraft is stationary, such as those which cause the wings to droop
since they are full of fuel.
Text Reference:
Y&F 1.79, 11.3
Theory
The force table allows us to balance the tension force(s) exerted by thin (massless)
strings on a center ring, such that the ring is suspended in space. Balance is defined
by the condition that the vector sum of forces is zero
G
F
=
0
∑
Eq. 1
This in turn means that the components of F
are separately zero, or
Σ
F
x
= 0 and
Σ
F
y
=0.
Eq. 2
In this handout we will indicate vectors with an underline symbol as vector F.
The tension force in a string is given by
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 Spring '08
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 Polar Coordinates, Force, tension force, statics problem, PHY122 Labs

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