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Physics of the Firearm |
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Physics of the Firearm
Common
Types of Rifles: ·
Bolt Action ![]() Image: http://www.savagearms.com/firearms/models/ ·
Lever Action ![]() Image: http://www.marlinfirearms.com/Firearms/xlr/444.asp ·
Semi-Automatic
Image:
http://www.remington.com/products/firearms/centerfire/model-750/model-750-woodsmaster.aspx
Of the above listed firearms the bolt action rifle
is the most widely used for hunting wild game so
that is the type of rifle I will be explaining the
physics of. Bolt
Action Rifle:
Looking at the image below you can see a
spring inside of the bolt. When the firearm is
charged, the spring is set in a compressed position.
Once the trigger is squeezed it releases the spring
and the spring drives the firing pin forward
striking the primer on the cartridge.
Image:
http://homestudy.ihea.com/aboutfirearms/05a_howfires.htm
In modern physics the spring can be explained using
Hooke’s Law while treating the length until the spring
is compressed as the value for “x” or displacement.
The equation is: F = kx. Using F = kx, the spring
constant, k, can be determined once all of the forces
are determined and the displacement is known by
rearranging the equation like this: k = F/xand
then solving for k. The restoring force of the spring
is then F = -kx. Another useful perspective into the
spring of a firearm is possibly looking at the energy
of the spring. As the spring is compressed the force
varies linearly and as seen from Hooke’s Law force is
proportional to displacement. Using this definition,
the total work to draw the spring back can be
calculated using the equation W = Fx, where W is work,
F is force, and x is the displacement of the spring
from rest. The spring’s potential energy can be
determined with the equation: U = 1/2 kx2.
The spring’s kinetic energy can be explained
using the conservation of energy law and a known value
for potential energy. The trigger is the releasing
mechanism for all of the potential energy in the
spring to turn into kinetic energy while the spring
works back to equilibrium.
Most firearms use a spring or similar system so
the interchangeability of these equations between
multiple firearms is very possible assuming the
mechanisms are known and are relevant to the
equations. There
are multiple other physics related data concerning
the firearm, especially when the bullet is fired,
however I chose only to use the spring as an
example. |