momentum is a vector quantity that is defined as the product of an object’s mass and velocity. p =...
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Momentum is a vector quantityThat is defined as the product
Of an object’s mass and velocity.
p = mv
A 2250 kg pickup truck has a Velocity of 25 m/s to the east.
What is the momentum of The truck?
56250 kg m/s
A 21 kg child is riding on a 5.9 kgBike with a velocity of 4.5 m/s To the north west. What is the
Total momentum of the child & bikeTogether? Just the child? Just
The bike?
120 kg m/s 94 kg m/s 27 kg m/s
A change in momentum Takes force and time.
FΔt = Δpor
FΔt = mvf - mvi
The Impulse-Momentum Theorem
Impulse (for a constant externalForce) is the product of the
Force and the time over whichIt acts on an object.
FΔt is called the Impulse.
A 1400 kg car moving westward With a velocity of 15 m/s
Collides with a utility pole. It is thenBrought to a stop in 0.30s. Find
The magnitude of the force Exerted on the car during the
Collision.
7 X 104N
Stopping times and distances Depend on the impulse-
Momentum theorem.
A change in momentum over A longer time requires less force.
Angular momentum is the productOf a rotating object’s moment
Of inertia and angular Speed about the same axis.
L = Iω
Erica, 65kg, is spinning on a merry-Go-round that has a mass of 115kg,
And a radius of 2m. She walks From the edge to the center. If
The angular speed is initially 2 rad/sWhat is its angular speed when she
Reaches a point 0.5m from The center?
3.9 rad/s
The angular impulse-momentumTheorem states that the angular
Impulse on an object is equalTo the change in the object’s
Angular momentum.
τΔt = Lf - Li
The total momentum of all objectsInteracting with one another
Remains constant regardless of The nature of the forces
Between the objects.
m1v1i + m2v2i = m1v1f + m2v2f
The conservation of momentumCan be shown as a formula…
Momentum is conserved in Collisions and for objects
Pushing away from each other.
A 76 kg boater (Charlie), initially At rest in a stationary 45 kg boat, Steps out of the boat and onto the
Dock. If Ryan moves out of theBoat with a velocity of 2.5 m/s,
What is the final velocity Of his boat?
v2f = 4.2 m/s
An 85 kg fisherman jumps from aDock into a 135 kg rowboat at restOn the west side of the dock. If the
Velocity of the fisherman is 4.3 m/s to the west, what is the
Final velocity of the Fisherman and the boat?
1.66 m/s to the west
There are two kinds of collisions:
Those that bounce off of each otherAnd those that stick together
A perfectly inelastic collision is aCollision in which two objectsStick together and move with
A common velocity afterColliding.
m1v1i + m2v2i = (m1 +m2) vf
The formula for a perfectly Inelastic collision
An 1850 kg Cadillac stopped at a Light is struck from the rear byA Honda with a mass of 975 kg. The 2 cars become entangled.
If the Honda was moving at 22 m/s to the north before, what Is the velocity of the entangled
Mess after the collision?
vf = 7.59 m/s to the north
A grocery shopper tosses a 9 kg Bag of dog food into a stationary18 kg cart. The bag hits the cart
With a horizontal speed of 5.5 m/sToward the front of the cart. What is the final speed of the
Cart and bag?
1.8 m/s
The law of conservation of Angular momentum states thatIf no external torque acts on an
Object, then its angular momentumDoes not change.
L1 = L2
Iω = Iω