Unformatted text preview: servation of
linear momentum. It can be expressed as (10)
Equation (10), says Total linear momentum
at some initial time t i Total linear momentum
at some final time t f (11) CAUTION: Momentum should NOT be confused with energy. Momentum can be conserved while the
energy would not be conserved. This is because Equation (10) is a vector equation and, as such, each
momentum term is equivalent to three equations corresponding to the conservation of linear momentum
in three mutually perpendicular directions as in an xyz coordinate system. Depending on the forces acting
on the system, linear momentum might be conserved in one or two direction, but not in all directions.
However, If the component of the net external force on a closed system is zero along an axis, then
the component of the linear momentum of the system along that axis cannot change.
As an example, suppose that you toss a grapefruit across a room. During its flight, the only
external force acting on the grapefruit (which we take as the system) is the gravitational force, wh...
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