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66 Cards in this Set
- Front
- Back
position
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location of an object
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distance
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space between two places
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speed
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how fast an object is moving (rate of change of position)
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constant speed
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doesn't change
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average speed
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total distance divided by total time
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instantaneous speed
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at the moment
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velocity
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how fast and what direction object is moving
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average speed formula
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v= d/t
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what is the speed of a truck that travels 15 miles in 20 minutes? (in mph)
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v= ?
d= 15 miles t= 20 minutes t=20 min x 1hr/60 min = .33 hrs 15 mi/.33 hrs = 45 mph |
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reference point
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frame of reference
"with respect to..." ***usually the earth*** |
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acceleration
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rate of change of velocity
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acceleration formula
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a= final velocity - initial velocity
--------------------------------- time |
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from rest a bike accelerates to 12 m/s in 25 s. what is the rate of acceleration?
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inital v= 0 m/s
final v= 12 m/s t= 25 s a=? a= 12 m/s - 0 m/s -------------- 25 s a= .48 m/s2 |
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unit for acceleration
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miles per second squared
m/s2 |
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unit for distance
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meters
m |
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unit for velocity
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miles per second
m/s |
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unit for time
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seconds
s |
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what are the positive and negative accelerations
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faster, starting --> positve
slower, stopping, turning --> negative |
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inertia
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objects resistance to changes in motion
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force
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push or pull that one object exerts on another
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what can change the velocity of an object?
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force
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balanced forces
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cancel each other out
same size moving in opposite directions **sum of all forces acting on object = 0 net force |
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unbalanced forces
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net force doesn't equal zero
cause acceleration |
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Newton's 1st Law of Motion
"Law of Inertia" |
-objects at rest stay at rest, objects in motion stay in moving in a straight line at a constant speed unless action on by an unbalanced forced
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gravity
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-force of attraction between two objects in the universe
-depends on mass and distance between them |
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properties of gravity
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bigger the mass, bigger force of gravity
bigger the distance, smaller force of gravity |
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friction
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force that opposes motion
-sliding -rolling -fluid (liquid/gas...air resistance) |
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Newton's 2nd Law of Motion
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-acceleration of an object increases as the net force on that object increases
-force increases, acceleration increases -mass increases, acceleration decreases (force is proportional to acceleration) |
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force formula
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force= mass x acceleration
f= m x a |
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unit for force
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kg x m/s2 ----> NEWTON
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max acceleration of a fist in a karate blow is 3500 m/s2. if the fist has a mass of .70 kg, how much force can the fist exert?
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F= ?
m= .70 kg a= 3500 m/s2 F= .70 kg x 3500 m/s2 F= 2450 N |
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weight
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-doesn't equal mass
-force of gravity between object and large body (planet) -depends on location -measured w/ scale and Newtons |
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mass
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-amount of matter
-measured in kilograms -constant everywhere |
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weight formula
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weight= mass x gravity
W= m x g |
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acceleration due to gravity
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9.8 m/s2
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unit for weight
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Newton
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unit for gravity
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m/s2
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what is the mass of a 400 N rock?
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m=?
W= 400 N g= 9.8 m/s2 400 N= m x 9.8m/s ----- ------ 9.8m/s2 9.8m/s2 m= 40.8 kg |
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falling objects
(neglect air resistance) |
everything falls at same rate of acceleration on earth (9.8 m/s2)
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falling objects
(w/ air resistance) |
-fluid friction= force that opposes motin
-depends on size, shape, speed (more speed, more air resistance) -eventually force of gravity equals air resistance (terminal velocity) |
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falling objects formula
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distance = 1/2 gravity x time squared
d= 1/2gt2 |
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projectile motion
-horizontal throwing |
v= d/t
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projectile motion
-dropping something |
a= final velocity - initial velocity
-------------------------------- time or d= 1/2gt2 |
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Newton's 3rd Law of Motion
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-forces always come in pairs (Action-Reaction Pair)
-when an object exerts a force on another object, then the 2nd object exerts the same size force in the opposite direction on the first object |
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centripetal force
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-causes circular motion
-always directed towards center of circle |
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centrifugal force
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no such thing
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centripetal acceleration
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acceleration towards the center of a circular path
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momentum formula
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momentum= mass x velocity
p=m x v |
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law of conversation of momentum
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momentum before a collision is equal to momentum after a collision
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work
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force applied over a distance in the same direction
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work formula
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Work= force x distance
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power
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how fast work is done
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power formula
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power= work
---- time |
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work formula
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Work= force x distance
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power
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how fast work is done
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power formula
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power= work
---- time |
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unit for work
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joule
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unit for power
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watt
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1 hp= ?
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550 ft-lb
---- s and 746 watts |
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energy
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ability to do work or to create a change in itself or its surroundings
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5 types of energy
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mechanical
chemical electromagnetic thermal nuclear |
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kinetic energy
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energy in form of motion of object
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kinetic energy formula
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KE = 1/2mv2
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potential energy
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energy due to objects position/condition (edge/stretched)
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potential energy formula
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PE= m x g x h
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units for kinetic and potential energy
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joule
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