• The momentum (P) of an object equals its mass times its velocity.
P = m * v
• Change in Momentum / Impulse
Impulse-Momentum Theory - The change in momentum,
called the impulse, is equal to the force times the change in time.
Impulse = F * t
Impulse = P2-P1
= mv2-mv1= m(v2-v1)
SO ... F * t = m(v2-v1)
• Angular Momentum
> ... is the product of an object's mass, velocity, and
distance from the center of rotation
> If the angular momentum is constant, then there is no
torque.
> As the distance from the center increases, the velocity
decreases.
• Conservation of Momentum
> The momentum in a closed, isolated system
does not change.
> The total momentum before a collision
equals the total momentum after a collision.
PTbefore
= PTafter
> If there are two objects that collide
and then move at separate velocities ...
PTbefore
=
PTafter
P1before + P2before
= P1after
+ P2after
m1v1before + m2*v2before = m1*v1after
+ m2*v2after
> If the two objects become attached, then the momentum
after is equal to the combined mass times the velocity of the pair.
m1* v1before + m2*v2before
= (m1+ m2) * vafter
So there’s only one velocity after ... that
of the combined mass. The mass after is equal to the sum of the two
masses that joined.
> If an object is at rest (before or
after), its velocity is zero.
> The masses of the two objects don’t
change (though they may be added if the masses stick together after the
collision). The velocities, however, may change.
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