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Linear Momentum


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Newtons Second Law
A law of motion that states that acceleration is equal to force divided by mass.
Newtons Third Law
A law of motion that states that for every action force here is a reaction force equal in strength and opposite in direction.
conservation of momentum
the total momentum of a system of objects does not change, as long as no outside forces are acting on that system.
Isolated System
A system that has are no energy transfers between that system and its surroundings.
system
A collection of components organized to accomplish a specific function or set of functions.
the magnitude of momentum
must add up to zero
impulse
a large change in momentum over a short period of time
inelastic collision
A collision in which the colliding objects become distorted, generate heat, and possibly stick together.
elastic collision
It occurs when both kinetic energy and momentum is conserved
Center of mass
same as center of gravity
poles
the parts of the magnet where the magnetic force is the strongest
North Pole and South Pole
The Pole of a freely suspended magnetic force which points to north or south
Ferrogmatic
materials that can be made into a magnet
magnetic field
a vector force field that surrounds any magnetic material
Magnetic Field Lines
The direction of the magnetic field at a given point can be defined as the direction that the north pole on a compass would point if placed on that point.
magnetic declination
the angular difference between magnetic north as represented on a compass and true north
Hans Christian Oersted
The compass needle effects the electric wire-the basics of a motor
An electric current
Produces a magnetic field
Domain
made up of regions 1mm in length with individual north and south poles that are allied in one direction, that makes up an electro magnet
Electro Magnetic Induction
production of a potential difference (voltage) across a conductor when it is exposed to a varying magnetic field.
Solenoid
A coil of insulated wire, usually wrapped around an iron core.
second right hand rule
The direction of the force on a current carrying wire in a magnetic field
Soft Iron
loses its magnetism easily when the current is turned on or off
Hard Iron
holds magnetism even without any externally applied field
commutator
Strips or bars of metal insulated from each other and arranged around one end of an armature. Used to flip the flow of electricity, so positive becomes negative and negative becomes positive.
motor
A device used to convert electric energy into mechanical energy.
generator
engine that converts mechanical energy into electrical energy by electromagnetic induction
circuit
when a continuous conducting path is connected between the terminals of a battery
electric current
charge per unit of time
conservation of electric charge
in any single circuit the current at any instant is the same at one point as at any other point
potential difference
the difference in electrical charge between two points in a circuit expressed in volts
rule for flow of charge
positive charge flowing in one direction is equivalent to negative charge flowing in the opposite direction.
Ohm's Law
for ohmic resistors: current is proportional to voltage at constant temperature. (V = RI)
nonohmic
materials that do not follow Ohm's law
resistors
used to control the amount of current in electronic devices
series creates
a greater potential voltage, causes a greater electric current flow
resistance
a force upon an object that slows down motion
Electric Charge
a property that leads to electromagnetic interations between the particles that make up matter.
Polar
the bond would be classified as _______ covalent if the electrons are shared unequally. an example of this would be the bond formed between hydrogen and chlorine
strong force
Force that attracts nucleons to each other within the nucleus; a force that is very strong at close distances but decreases rapidly as the distance increases. Also called strong interaction.
conductors
electrons are loosely bound to the nucleus making it easier to collect electrons
electroscope
device used for detecting charge
charging by induction
when a positive rod is close to but not touching a neutral rod the neutral rod will distribute its negative electrons to the side closest to the positive rod and protons farthest from the positive rod
Coulomb
SI unit for charge
source charge
creates the electric field
test charge
what enters the electric field and is affected by it but its magnitude is much smaller than the source charge
charging by conduction
the process of charging a neutral object by touching it with a charged object
electric field
extends outward from every charge and permeates all of space, it is in the same direction of the force that a positive test charge would experience if it entered the field.
positive source charge
electric field lines go outward
negative source charge
electric field lines go inward
positive test charge
the force and the electric field are in the same direction
negative test charge
the force and the electric field are in opposite directions
Law of conservation of electric charge
The net amount of electric charge produced in any process is zero
heat
The transfer or exchange of thermal energy caused by a temperature difference
Thermal/Internal energy
total amount of molecules in a body
Calorie
cal
temperature
increase in temperature increases the average kinetic energy of the particles
Specific Heat
Amount of heat needed to raise the temperature of 1kg of material 1 degree Celsius.
Latent
hidden
latent heat
when heat is added but temperature dosent increase
Latent heat of Fusion
liquid to a solid and reverse
Latent heat of vaporization
liquid to gas and reverse
rate of heat flow rule 1
As thickness goes up the rate of heat flow goes down
rate of heat flow rule 2
if there is a large temperature difference, there is a larger rate of heat flow
cross sectional area
rate of heat flow rule 3
convection
the process whereby heat is transferred by the mass movement of molecules from one place to the other
forced convection
example: furnace: forcibly pushes air around house
natural convection
wind: hot air rising because it is less dense than cool air
Radiation
energy that is radiated or transmitted in the form of rays or waves or particles
hurricane
natural purpose of bringing thermal energy to polar regions from equilateral regions
Fluid
A gas or a liquid
Pnematics
the use of gas/air on an enclosed system under pressure
hydrolics
Study of liquids at rest and in motion, specially under pressure-multiplier and lets you change the direction of the force- Newton's in= Newton's out
Atmosphere
1 atm= 1.3 x 10 to the 5th
Pressure Head
pressure derived from linear height from the top of a surface of a liquid
Density
Mass per unit of volume (m/v)
Absolute Pressure
Gauge Pressure + Atmospheric Pressure
Gauge Pressure
How much below and above pressure there is
music
vibration of molecules rubbing against eachother
viscosity
resistance to flow (molecules with large intermolecular forces);
hydrometer
measures Specific Gravity - if the hydrometer is lower in the liquid - the liquid is less dense
anemometer
a device for recording the speed and direction of wind-uses pressure generated by wind to measure its speed
suction
lowering pressure in between so atmospheric pressure will push both cups together
Laminer
parallel layers of fluid
turbulent
layers of fluid that cross over each other and create friction
continuity
what comes in must go out
Pascals Principle
The pressure applied to a confined fluid increases the pressure throughout by the same amount
Open tube Manometer
measuring pressure by the difference in height of the two levels of liquid
Boyant Force
weight of the fluid displaced-the deeper the object, the greater the pressure *wink, wink*
Archimedes Principle 1
the boyant force on an object is equal to the weight of the fluid displaced
Archimedes Principle 2
An object will float if its density is less then the fluid its in
Archimedes Principle 3
How much an object is submerged is directly proportional to the ratio of the density of the object to the density of the fluid
apparent weight
the force exerted on a scale by an object and other forces acting upon the object is the _______.
Bernouli's Principle
as the speed of a fluid (usually air or water) increases, the pressure within the fluid decreases.
vector
a displacement distinguished by magnitude and direction but not by location.
scalar
a physical quantity that has magnitude but no direction
rate of change of momentum
the net force applied to the object
conservation of kinetic energy
all collisions must be perfectly elastic; system must be isolated problems
Electric Field Lines
1)show the sign of the source charge.2) show the direction of the electrostatic force at a particular point.3) show the relative magnitude of the source charge
What factors affect an object's momentum?
A moving object can have a large momentum if it has a large mass, a high speed, or both
What factors affect how much an object's momentum changes?
Depends on the force that acts and the length of time it acts
What does the law of conservation of momentum state?
It states that in the absence of an external force, the momentum of a system remains unchanged.
How does the conservation of momentum apply to collisions?
Whenever objects collide in the absence of external forces, the net momentum of both objects before the collision equals the net momentum after the collision.
What is true about the vector sum of momenta in a collision?
It is the same before and after a collision. (momentum is conserved)
external force
a force applied to a system from outside the system, the most common of which are weight, support or normal force, friction, and fluid resistance
Closed System
A system containing a fixed amount of matter; it can still exchange energy with the surroundings.
momentum
(p) vector quantity describing the quantity of motion or inertia in motion. Recognizes that both mass and velocity have a part in the motion of an object and is proportional to both (is zero …
inelastic interaction
a collision in which the colliding objects become tangled or coupled together, distorted (shape changes) and/or generate heat or sound during the collision
elastic interaction
collisions in which colliding objects rebound without a lasting change in shape or sound or heart generation
kinetic energy
a running dog
explosive interaction
an interaction in which the objects of the system are initially at rest before the parts interact and fly apart because of the release of energy stored within the system
impulse-momentum theorem
an impulse causes and is equal to the resulting change in momentum and is in the same direction as the change of momentum
Energy
(physics) the capacity of a physical system to do work
impact
a term often used to describe the force when one object hits another
Law of Conservation of Momentum
If no external forces act on a system, then the total momentum of that system remains the same
conservation
amount never changes within a closed and isolated system
Linear Momentum
Linear momentum of an object is its mass times its velocity. Since momentum does not have a unit
Example of Momentum
the equal force applied by a wall when you push agaginst it
Conservation of Energy
Energy cannot be created or destroyed; it may be transformed from one form into another, but the total amount of energy never changes
When is momentum conserved?
When the outside force acting on the system is zero
internal force
force included in the system
Definition of Conservation of Momentum
For a collision or explosion occurring between object 1 and object 2, the total momentum of the two objects before is equal to the total momentum of the two objects after
Word equation for Conservation of Momentum
Initial momentum (mass multiplied by velocity) of object 1 plus initial momentum of object 2 is equal to final momentum of object 1 plus final momentum of object 2
Equation for Conservation of Momentum
m₁u₁ + m₂u₂ = m₁v₁ + m₂v₂
Momentum unit
kilogram metre per second (kgm/s)
Velocity unit
metre per second (m/s)
Mass unit
kilogram (kg)
L
angular momentum
L=
Iw
I
strong nucleophile, best leaving group
I=
1/2mr^2
w
angular speed
w=
wo+fish x time
fish
angular acceleration
P=
mass x velocity or mv
J
impulse
J=
Ft or (change in momentum)
change in momentum
Force x time
Ft=(short)
mass x acceleration x time
Ft= (longer)
(mass x final velocity) - (mass x initial velocity)
F=
(-mass x initial velocity) / time
a=
(velocity- initial velocity) / time
units for impulse
Ns or kgm/s
in an elastic collision...
kinetic energy is conserved
in an inelastic collision...
kinetic energy is NOT conserved
KE=
1/2mv^2
v=
2πr/T=
conservation of momentum=
m1 x v1 = m1 x v1 + m2 x v2
conservation of kinetic=
1/2 x m1 x v1^2 = 1/2 x m1 x v1^2 + 1/2m2 x v2^2
explosive=
P=mv
x=
the square root of (mv^2)/k
Distance
a path taken and always a positive number
mew x mg
Force of friction Ff
1/2 I w^2
Kr (constant x radius)
p-initial = p-final / p1-initial + p2-initial = p1-final + p2-final
What is the equation for the law of conservation of momentum if you are dealing with one object? Multiple objects?
inelastic conditions
objects stick together
elastic collisions
objects bounce off each other
inelastic
In what kind of collision do the object have the same final velocity?
both inelastic and elastic
In what kind of collision is momentum conserved?
KE, due to deformation
In an inelastic collision, what is lost and why?
<
KE-initial __ KE-final?
P-initial = P-final
What is the equation of an inelastic collision?
=, conserved
KE-initial __ KE-final, so KE is _______?
both, x, y
If a collision occurs in two dimensions, momentum will be conserved in _______ dimensions, so you could have _______ and _______ momentum.
In an elastic collision, it is being assumed that the objects _______.
don't compress, which in terms of plausibility is the equivalent of friction or air resistance being absent
What does momentum refer to?
the quantity of motion an object has
mass, mass, motion, momentum
All object have _______, so when they are moving, they have _______ in _______, and therefore _______.
What two variables is momentum dependent on?
how much is moving -- mass -- and how fast its moving -- velocity
p = m(v)
What is the equation for momentum?
mass, velocity
Momentum is directly proportional to _______ and _______.
kg(m/s)
What is the standard unit of momentum?
false: momentum always has the same direction as velocity
true/false: if the velocity vector of an object is positive, its momentum can still be negative.
stop
The more momentum an object has, the harder it is to _______.
To stop something with momentum, a _______.
force must be applied over a given period of time
greater, longer
The more momentum an object has, the _______ the force applied will have to be or the _______ the amount of time it will take to stop it.
accelerates
An unbalanced force always _______ an object.
F(t) or m(Δv)
What is the equation for impulse?
impulse-momentum change equation
What is the equation for impulse also known as?
In a collision, what happens to the momentum of the two objects and why? What theorem states this?
momentum changes because force is applied to the two objects over a given period of time, causing a change in velocity / impulse-momentum change theorem
Inversely
Acceleration is _______ proportional to mass
100
If an object has 100 units of momentum, it takes _______ units of impulse to stop it.
1,2,4
If there are 100 units of force, over what period of time must that force must be applied to produce 100 units of impulse? How long if there are 50 units of force? 25?
time over which it is applied
To minimize the force on an object involved in a collision, the _______ must be increased.
standing still and let the fist hit you
If someone is about to be punched, which will minimize the force of the punch: standing still or running head on into the punch?
LOOK AT THE EXAMPLES IN THE READING
What else should you do to study this information for the test?
rebounding
the act of two objects bouncing off each other as a result of their collision
velocity and momentum
Rebounding is characterized by large changes in _______.
crumple zones
sections of cars that are designed to crumple up when the car encounters a collision so as to minimize the force in an automobile collision
magnitude, direction, speed up, gain momentum, slow down, lose momentum
In a collision, both objects experience forces that are equal in _______ and opposite in _______. This causes one object to _______ or _______ and the other to _______ or _______.
accelerations
In a collision, if two objects have unequal masses, they will have unequal _______ resulting from the contact forces of the collision.
least
In a collision, the _______ massive object receives the greatest acceleration.
Why?
because both person a and B cover the same angle in the same time
- force must originate from a source other than the two objects of the system
What two conditions must be met for a system to be being acted upon by an external force?
false: it is considered isolated
True/False: A system in which the forces of each object act on the other object is not considered isolated.
yes, yes STUDY QUESTIONS ON ISOLATED SYSTEMS PAGE
Two billiard balls collide on a table with a negligible force of friction. The only forces acting on each ball are the forces applied by the other ball when the two collide. Is this sy…
no
Can velocity ever be greater than speed?
no because of friction
Is it feasible that one can have a perfectly isolated system? Why or why or why not?
it is extremely accurate and the force of friction is often negligable
Why is the Theory of Conservation of Momentum still applicable despite the inevitability of friction being present?
yes: an internal force is propelling objects (usually fragments) away from each other
Does the law of conservation of momentum apply to explosions? If yes, how so?
add the vector sums of all of the objects together / yes
How could you find the momentum of the total momentum of a post-explosion system? Would it be the same as the momentum of the system pre-explosion?
No: (kg)(m/s)
Does momentum have a derived unit? What is its unit?
p=mv
What is the equation for momentum?
what is the equation for impulse?
J = Δp or J = mΔv or J = mat or J = Ft