second exam
conservation of linear momentum- if the net external force on a system is zero, the total linear momentum of the system doesn’t change
conserved- a number associated with a physical property doesn’t change over time
impulse- the product of the force and time during which it acts, F x delta t. this vector quantity is equal to the change in momentum
linear momentum- p=mv
elastic- collision or interaction where KE is conserved
gravitational potential energy- GPE=mgh
inelastic- collision or interaction where KE is not conserved
joule- SI unity of energy and work
kinetic energy- KE= 1/2mv^2 (m is mass and v is speed)
mechanical energy- sum of KE and various potential energies, may include gravitational and elastic potential energies
power- rate at which energy is converted from one form to another, P= delta E/ delta t. measures in watts
watt- SI unit of power, 1 joule per second
work- W=Fd measured in joules
angular displacement- The change in angular position, mea- sured in degrees, radians, or number of revolutions.
angular momentum- A quantity giving the rotational momentum. For an object orbiting a point, it is the product of the linear momentum and the radius of the path, L = mvr. For a spinning object, it is the product of the rotational inertia and the rotational speed, L = iw.
center of mass- The balance point of an object. This location has the same translational motion as the object would if it were shrunk to a point.
conservation of angular momentum- If the net external torque on a system is zero, the total angular momentum of the system does not change.
rotational acceleration- The change in rotational velocity divided by the time it takes to make the change.
rotational inertia- property of an object that measures its resistance to a change in its rotational speed
rotational kinetic energy- KE associated with rotation of a body KE= 1/2iw^2
rotational speed- angle of rotation or revolution divided by time taken. rps or rpm
rotational velocity- vector quantity that includes the rotational speed and direction of the axis of rotation
stable equilibrium- equilibrium position or orientation to which an object returns after being slightly displaced
torque- rotational analog of force T=rF
unstable equilibrium- an equilibrium position or orientation that an object leaves after being slightly displaced
centrifugal force- fictitious force arising when a reference system rotates or changes direction. point away from center, opposite from the centripetal acceleration
coriolis force- fictiticious force that occurs in rotating reference systems, responsible for direction of winds in hurricanes
principle of relativity- laws of motion are the same in all inertial reference systems
geocentric- model of universe w/ earth in the center
heliocentric- model with sun at center
inertial force- A fictitious force that arises in accelerating (noninertial) reference systems. Examples are the centrifugal and Coriolis forces.
inertial reference system- any reference system in which the law of inertia is valid
noninertial reference system- any reference system where law of inertia is not valid, accelerating reference system is noninertial
reference system- collection of objects not moving relative to eachother that can be used to describe the motion of other objects
equivalence principle- constant acceleration is completely equivalent to a uniform gravitational field
ether- hypothesized medium through which light was believed to travel
first postulate of special relativity- the laws of physics are the same for all inertial reference systems
general theory of relativity- an extension of the special theory of relativity to include the concept of gravity
gravitational mass- property of a particle that determines the strength of its gravitational interaction with other particles. measured in kg
inertial mass- an objects resistance to change in its velocity. measured in kg
rest-mass energy- energy associated with the mass of a particle E=mc^2 where c is speed of light
second postulate of special relativity- speed of light in a vacuum is a constant regardless of the speed of the source or speed of observer
spacetime- combination of time and 3d space that forms a 4d geometry.
special theory of relativity- comprehensive theory of space and time that replaces newtonian mechanics when velocities get very high
absolute temperature scale- kelvin
atomic mass unit- one twelfth off the mass of a carbon atom, one amu is 1.66 x 10^-27
avogrado’s numer- 6.02 x 1023, # of molecules in 1 mole of any substance
compound- combination of chemical elements that forms a substance with its own properties
ideal gas- enourmous number of tiny particles separated by relatively large distances, particles have no structure, are indestructable, and dont interact except for collisions, which are ELASTIC
ideal gas law- PV=nRT, p-pressure, v-volume, t- absolute temp, n- moles, r- gas constant
law of definite proportions- when 2+ elements combine to form a compound, the ratios of the masses of the combining elements have fixed values
macroscopic- describes bulk properties like mass, size, pressure, temp
microscopic- describes properties not visible to eye like atomic speeds or the masses and sizes of atoms
moles- amount of a substance that has a mass in g numerically equal to the mass of its molecules in amu
molecule- combination of 2 or more atoms
pressure- force per unit area of surface, measures in newtons per square peter or pascals