Types of Simple Forces
1 There are different types of
forces that act in different ways on
structures such as bridges, chairs, buildings, and even people. The
main examples of
these forces are explained below. Study the descriptions in this text
and
then draw a diagram or picture to represent each of these forces.
1.1 A Static Load : A good
example of a static load is a person holding
a stack of books while waiting in a line but not moving. The downward
force is STATIC.
1.2 A Dynamic Load : A good
example of a dynamic load is the person carrying
the same books but walking. The downward force is a complex set of
moving or DYNAMIC force.
1.3 Internal Resistance : A
person sitting on a bicycle with air filled
tires is placing great pressure through the tire to the ground. The
air pressure inside of the tire pushes back against the riders weight
and causes INTERNAL RESISTANCE.
1.4 Tension : A rope is in
tension as two people push1
on it. This stress places the rope in TENSION.
1.5 Compression : A weight
lifter finds that his body is compressed ( being smashed) by the
weight(s) that he is holding above his head.
1.6 Shear Forces : A good
example of shear force can be seen with a pair
of scissors. The handles put force in different directions on a pin
(usually a screw) that holds the two halves of the shears together.
The force applied to the connecting pin is called shear force.
Footnotes:
1That is
right, I said push. Physically it is impossible to "pull"
anything. For example when you grasp a rope you are actually
pressing/pushing
your hands into the surface of the rope - any force is then transmitted
through the surface of your hands through the ropes tension. The same
analogy can be made for a railway locomotive and a trailing car.
The couplers are actually pushing against each other, the inside of
the leading coupler presses against the back of the trailing/following
coupler.
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On 17 Dec 2005, 20:07.