Momentum - Harrison High School

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Transcript Momentum - Harrison High School

Unit 5
What is Momentum?
Momentum: ___________ in motion
Momentum= Mass x Velocity
____________ = Mass x Speed – when direction is
not an important factor
Unit: kg x m/s
The more __________ an object has, the more
__________ there is possible.
Speed affects the momentum of an object.
EX. A fast car can have more momentum than a slow truck
w/ greater mass
Non-moving objects have no momentum at all.
Impulse Changes Momentum
 If ____________ changes,
then either mass or velocity
or both has changed.
 If mass is unchanged and
the ___________ changes
then acceleration results.
 Accelerations are produced
by Forces.
 The greater the force=
______ an objects change
in velocity = Greater
change in momentum.
 The quantity force X time
interval = Impulse
 F(delta t) = Impulse
 The greater the impulse on an
object, the greater the
_____________ in momentum
 Impulse = _____________ in
 Impulse = Ft = delta (mv)
 t is the time interval (delta t)
 Unit = Ns
Increasing Momentum
 Apply greatest force possible for as long as possible.
 EX. Baseball player and Golfer swinging as hard as possible
and following through with their swings.
 Forces involved in impulses usually vary from ________
to instant.
 EX. The force is zero on a golf ball until it is struck by
the club; then the force increases rapidly as the ball’s
shape becomes distorted. The force decreases as the
ball returns to its original shape and increases in speed
 _________________= Avg. force of impact measured in
 __________________ = Impact Force x time measured
in Newton seconds
Decreasing Momentum
 The same impulse decreases your momentum
whether hitting a wall or haystack
 The same impulse does ______ mean with the
same force or time.
 The product of the force and time are the samenot necessarily the force and time.
 Impact time is ______________ when you hit the
haystack rather than the wall.
 Impact time = the time during which your
momentum is brought to _________.
 The ___________ the impact time = reduction in
force of impact = reduction in deceleration
 EX of things that increase impact time and therefore
decrease impact force
 Airbags
 Padded dashboard v. rigid dashboard
 Bending your knees when you jump from an elevated
 Relaxing your body when you fall to spread force of impact
over more muscles
 Falling on a soft mat vs. hard floor
 Moving away from a punch
 EX. Increasing the time of impact 100 times reduces
force of impact 100 times.
 Impact force and impact time are ___________
proportional.(Two variables that affect impulse)
Conservation of Momentum
 To accelerate an object, a ______ force must
be applied to the object.
 To change the momentum of an object, you
must __________ an impulse on it.
 If no net force or net impulse acts on a system,
the __________ of that system cannot change.
 The Law of Conservation of Momentum: In the
absence of an external force, the momentum of
a system remains unchanged.
Elastic Collisions
 Elastic Collisions: When objects collide
___________ being permanently
deformed and without generating heat.
 Perfectly elastic collisions are not
common in the everyday world- some
__________ is produced in the collisions.
Inelastic Collisions
 Inelastic Collisions: objects collide and
become __________ or ___________
together generating heat and becoming
____________ in the process.
 Most collisions usually involve some
______________ force.