Download Momentum Notes

Momentum Notes
Momentum
Momentum (ρ)=
Mass x Velocity
ρ = mv
ρ = momentum (kg·m/s)
m= mass (kg)
v= velocity (m/s)
Momentum
Linear momentum of an object of mass
m moving with a velocity v is the
product of the mass and velocity
Inertia in motion
Law of Conservation of
Momentum
Law of conservation of
momentum says that in the
absence of an external force,
the total momentum of a
system remains unchanged.
Law of Conservation of
Momentum – Continued
1) This law applies to a
closed system (one
where no mass is gained
or lost)
Law of Conservation of
Momentum – Continued
Momentum conserved if:
2)
At all times, only two
objects are involved
3) The only forces involved
are internal
Impulse
I=Ft
I= impulse (N*s)
F=force (N)
t= time (s)
Also
Ft=mv2-mv1
F=Force (N)
m=mass (kg)
v=velocity (m/s)
Impulses
Product of the average net
force exerted on an object
and the time interval over
which the force acts.
F•t = impulse (I)
Impulses are measured in N•s
Impulse/Momentum
Theorem
Impulse of an object is
equal to the change in
momentum it causes
F • t = mv2 – mv1
Impulse
If you extend the time of
impact you reduce the
amount of force.
Types of Collisions
Elastic Collisions – when
objects collide without being
permanently deformed and
without generating heat
Ex: Billiard balls colliding
Elastic Collisions
m1v1 + m2v2 = m1v1 + m2v2
st
m1=mass of 1 object (kg)
v1=velocity of 1st object(m/s)
m2= mass of 2nd object(kg)
nd
v2=velocity of 2 object(m/s)
Types of Collisions
Inelastic Collisions –
whenever colliding objects
become tangled or couple
together
Ex: Two freight train cars
hitting and continuing
Inelastic Collision
m1v1 + m2v2 = mtotalvtotal
m1=mass of 1st object (kg)
v1=velocity of 1st object(m/s)
m2= mass of 2nd object(kg)
v2=velocity of 2nd object(m/s)
mtot= 1st and 2nd mass added
vtot= final velocity of both
Calculations
momentum before
collision = momentum
after collision
ρbefore = ρafter
ρ1 + ρ2= ρ1 + ρ2