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2012-07-02 06:47:41
physics final

physic's final chapters 1-17
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  1. an object that is moving, they help to explain acceleration
    motion diagram
  2. focus's on a single point, assumes object is a single point (example: door handle)
    particle model
  3. any push or pull, ____ is a vector
  4. quantity that has direction magnitude-size or length adds in a special way
  5. quantity in which direction is not important (example: takes me 5 seconds to walk to the end of the hallway)
  6. an arrow from a reference point to a point of interest (maybe chosen everywhere)
    postion vector
  7. arrow is a vector symbol arrow always points to the right, for r1 the magnitude is 2m and the diection is 45 degrees
    vector symbol
  8. in a straight line path from an earler point to a later point
    displacement vector
  9. speed and direction
  10. the result of adding together two or more vectors
  11. pick a scale for the length of the arrows
    draw an arrow representing one of the vectors
    place another arrow representing on of the other vectors with its tail at the first arrows tips
    contiued with step 3 until all the arrows tips are at the arrows tails
    the resultant is the arrow from the tail of the first to the tip of the last
    graphical method of adding vectors (tip to tail method)
  12. put tails at same point
  13. put tails at same point
    complete the parallelagram draw in a side parallel, to a and b with the same length
    the resultant goes from the point it started to the opposite side (A+B)
    parallelogram method of adding vectors
  14. a negative vector has the same magnitude but the exact opposite direction
    vector subtracting
  15. take the distance and divide by the time
    average speed
  16. speed at the moment in time
    instantaneous speed
  17. average velocity = displacement divived by time taken
    velocity of average speed
  18. ____ points in the same direction as displacement, in motion diagrams displacement vectors will be used to represent average velocities
    average velocity
  19. the rate of change of velocity
    1.) speed up
    2.) slowing down
    3.)changing direction
  20. _____ =change in velocity divided by the time taken
    average acceleration
  21. if the acceleration is facing the same direction of velocity it is ____
    speeding up
  22. if the acceleration is facing a different direction of velocity its ____
    slowing down
  23. one moment of time shorter than any mesasurement of time
    an instant
  24. _____ of time has zero length
    a moment
  25. only two possible directions of motions
    one dimension linear motion
  26. amount of change in velocity in one unit (one second)
  27. if gravity is the only force acting on an object the objuect with have a downward acceleration of 9.8 m/s
  28. the highest point of acceleration=
  29. usually called normal forces perpendicualr forces symbol is n(with arrow above)
    compression forces
  30. force exerted by a stretched elastic object as it tries to return to its natural shape (bungie cord ropes steel cables) symbol: T-->)
    pulls inwards at both ends
    tension forces
  31. force exterted by a spring symbol: fsp->
    spring force
  32. force exerted by a solid that always opposes mortion
  33. prevents an object from starting to slide
    static friction
  34. opposes a sliding object we will assume fk does not change with speed
    kinetic friction
  35. friction between a rolling object opposes a rolling object
    rolling friction
  36. force exerted by a liquid or gas that always opposes motion
  37. force exerted by expelling gas or liquid at high speeds
  38. the net force of air pressure on most objects is close to zero so we will ignore air pressure
    air pressure
  39. net force is called
    resultant force
  40. picture showing all the forces acting on a certain object
    for the particle model
    free body diagram
  41. the tendency of an object to resist changes in its velocity and all objects have inertia bowling ball has more inertia than a basketball
  42. measure of an objects inertia the units of mass are kg, g, mg
  43. is the force of gravity on an object units of weight newtons
  44. an objects mass is the same everywhere, an objects weight depends on location
  45. straightline through origin
    direct proprtionality
  46. every measureable quanity has only one unit
    si units
  47. interpenetration of hills and valleys on surfaces
    surface roughness
  48. chemical bond for only when they are touching, if you have two very smooth surfaces you can get alot of chemical bonds and large friction
    chemical bonding
  49. kinetic and rolling friction dont depend on speed
    fsmas, fk, and fr are all proportional to the normal forces
  50. object moving at constant speed
    uniform circular motion
  51. acceleration always points towars the middle of the circle
  52. same direction speeding up, deals with speed
    acceleration parallel
  53. change of direction, if a perpendicular is opposite then it is slowing down, if direction of a perpendicular shows direction of object is curving
    acceleration perpendicular
  54. r axis is towards center of the circle
    t axis tangetial to circle with positive t in counterclockwise direction
    z axis perpendicular to the plane of motion
  55. force towards the center of the circle would be static friction
  56. rate of going in a circle most common unit rpm, symbol w-omega
    angular velocity
  57. direction of a force and where you apply the force makes a difference
  58. line around which an object is rotating
    axis of rotation
  59. a single point
  60. turning effect of a force, radial forces cannot create torque only tangential forces can
  61. distance from axis to point where force is applied times the tangentail component of force
  62. + for counterclock wise, - for clockwise
  63. angle between r axis and force
  64. ___ is located at center of gravity from one point
  65. all objects have a singel point called
    center of gravity
  66. to calculate torque due to gravity, the entire wieght of the object can be assumed to pull down at the cg for a symetic uniform object cg is at the objects geometric center
  67. if an object is at rest and supported at a single point the cg must be either directly below the support point
  68. is what changes an objects rotation(speeding up or slowing down)
  69. the net force equals zero
    the net torque equals zero- cannot rotate
    static equalibrium
  70. pick an object to focus on
    draw a free body diagram of this object
    choose a pivot point
    calculate torque about this pivot for all the forces
    applying sum of torque = zero
  71. forces always occur in pairs, they are in opposite directions
    forces always exerts a force back on one another
    action reaction pair
  72. states that every action has an equal and opposite direction reaction
    whenever one object exerts a force on a second object the second object exerts an equal and opposite force back on the first object
    newtons third law
  73. ____ are equal (at the bumpers)
    contact forces
  74. depends on acceleration, larger acceleration usually menas more internal damage (on the drivers)
    internal forces
  75. mass times velocity
  76. the more force you have the bigger the impulse
    impulse momentum theorum
  77. one or more objects we consider as a unit, a group of objects we wish to study
  78. everything else
  79. force one part of system exerts on another part of system
    internal force
  80. force enviornment exerts on a system
    external force
  81. equals the sum of momentum of a system
    total momentum system
  82. if the net external force on system equals zero a systems total momentum remains constant
    internal forces cannot change total momentum of a system
  83. choose a system
    does net external force equal zero
    choose inital and final times
    then solve pf = pi
    using the law of conservation of momentum
  84. if delta t is very small the impuse and delta p is very small
    if there is firiction then they would be different, the net system would not equal zero
  85. if delta t is small enough total momentum of the system is conderved even if they net external force doesnt equal zero
    impulse approximation
  86. can normally be used in
    explosions-situations where internal forces cause an object to suddenly split apart into two or more parts
    impuls approximations
  87. objects stick together
    inelastic collision
  88. postive work means F is enhancing the motion
    negative work means F is opposing motion
  89. is one in which the work done by this force just depends on inital and final postion not depended on the path
    conservative force
  90. is the ability to do positive work
  91. is the ability to do work because of motion and speed
    kinetic energy
  92. ability to do work because of height
    gravitational poetential energy
  93. ability to do work because of the stretching or comressing of an elastic object
    elastic potential energy
  94. ability to do work because of temperature
    thermal energy
  95. ability to do work because of chemical reactions
  96. are always associated with conservative forces
    when the ball was thrown kinetic energy increased while chemical energy decreases
    potential energies
  97. work done by external forces
    external work
  98. choose a system to focus on when using Ug, earth must be part of the system
    chooose initial and final times
    calculate external forces Wext
    calculate change in each system
    solve the energy equation
    steps in using energy equation
  99. creates thermal energy
    where delta s is the total distance traveled against Fdiss, it is not dissplacement
    with _____ both objects must be included in the system bc they both gain thermal energy
    dissipative forces
  100. the random motion of the atoms of a substance
    thermal motion
  101. rate of doing work or the rate of gaining or using up energy
  102. energy of a substance due to thermal potion two parts of Eth
    kinetic energy of the atoms
    a form of Us due to the stretching and compressing of chemical bonds
    thermal energy
  103. is a measure of the aberage random kinetic energy of the atoms of a substance
  104. boiling point of water 100 degrees
    freezing point 0 degrees
    absolue zero -273
    celsius scale
  105. absolute zero- 0
    freezing point- 273
    boiling point - 373
    kelvin scale
  106. everything at same temperature
    thermal equalibrium
  107. transfers from hotter objects to the cooler objects because of atomic collisions or radiation
    thermal energy
  108. thermal energy that transfers froma hotter object to a cooler object
  109. amount of heat needed to increase 1kg of the material by 1 degrees celsius
    can be thought of as thermal inertia
    specific heat
  110. the more atoms there are in a kg of material the more heat it requires to increase the temperature
  111. force divided by area
  112. average pressure at sea levelĀ  atm
    atmospheric pressure
  113. when a gas expands Wext is negative with heat
    when a gas compresses Wext is positive
    first law of thermodynamics
  114. thermally insulated heat =zero delta Eth is positive
    adiabatic compression
  115. heat = zero delta Eth is negative temperature decreases
    adiabatic expansion