Glencoe Physics Chapter 9 Momentum and Its Conservation
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25.07.2018
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Baseball Why are baseball players encouraged to “follow through” when hitting the ball with a bat
Highway safety What can we do to make highways safer for people
A team that has a lot
Refers to how hard something is to stop .
So momentum of an object depends on the amount of stuff moving (mass) , and the velocity at which the stuff is moving.
Equivalent Momenta Momentum Facts
Momentum is a conserved quantity
Something big and slow can have the same momentum of something small and fast
Sample problems Calculate the velocity of a car that has a mass of 2175 kg and the same momentum as the previous car.
Glencoe Physics Chapter 9
Momentum
and Its Conservation
Air Bags
How exactly does an airbag prevent serious injury in an auto accident?
Baseball
Why are baseball players encouraged to “follow through” when hitting the ball with a bat?
Why does a cannon move backward when firing?
Highway safety
What can we do to make highways safer for people?
Common usage of the term “Momentum”
A team that has momentum is on
the
move
and is going to take some effort to stop.
“Going into the final weeks, the St.
Louis Cardinals have the
momentum
."
The headlines declare “Pittsburgh Steelers Gaining
Momentum
."
A team that has a
lot
of momentum is really
on the move
and is going to be
hard to stop
.
Momentum (from latin, meaning movement)
Momentum is a physics term
; it refers to the
quantity of motion
that an object has.
Refers to how
hard
something is to stop
.
Momentum Defined
So momentum of an object depends on the
amount of stuff moving (mass)
, and the
velocity
at which the stuff is moving.
Question?
Under what conditions of motion would a semi-truck and a roller skate have the same momentum?
Equivalent
Momenta
Momentum Facts
Momentum is a vector quantity
Velocity and momentum vectors point in the same direction
SI unit is the kg·m/s ( no special name)
Momentum
is a conserved quantity
Momentum is directly proportional to mass and velocity of object
Momentum Facts
A net force is needed to change a particular object’s momentum (a change in velocity)
Something big and slow can have the same momentum of something small and fast
Momentum
Examples
Sample problems
Find the magnitude of the momentum of a car of mass 725 kg moving at a velocity of 100. km/h.
Sample problems
Calculate the velocity of a car that has a mass of 2175 kg and the same momentum as the previous car.
Impulse
In
order to
change
the momentum of an object, a force must be applied
Gives an alternative statement of Newton’s second law…..
Watch as a little mathematical magic is performed!
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