# physic's

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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
force
4. quantity that has direction magnitude-size or length adds in a special way
vector
5. quantity in which direction is not important (example: takes me 5 seconds to walk to the end of the hallway)
scalar
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
velocity
10. the result of adding together two or more vectors
resultant
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
acceleration
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
horizontal
vertical
one dimension linear motion
26. amount of change in velocity in one unit (one second)
acceleration
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=
-9.8m/s
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
friction
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
drag
37. force exerted by expelling gas or liquid at high speeds
thrust
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
inertia
42. measure of an objects inertia the units of mass are kg, g, mg
mass
43. is the force of gravity on an object units of weight newtons
weight
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
torque
58. line around which an object is rotating
axis of rotation
59. a single point
pivot
60. turning effect of a force, radial forces cannot create torque only tangential forces can
torque
61. distance from axis to point where force is applied times the tangentail component of force
torque
62. + for counterclock wise, - for clockwise
torque
63. angle between r axis and force
phi
64. ___ is located at center of gravity from one point
force
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)
torque
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
solve
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
momentum
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
system
78. everything else
enviornment
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
collisions
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
energy
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
power
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
temperature
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
heat
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
pressure
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