# Shared Flashcard Set

## Details

Physics 1st Semester
Prentice Hall Physics Chapters 14-16
32
Physics
01/23/2012

Term
 Work
Definition
 done when some of the force acts on an object in the direction the object moves. force x distance = Work (J)
Term
 Joules
Definition
 N x m
Term
 Power
Definition
 rate of doing work, faster rate = move power neededWork/Time = Power (watts)
Term
 Watts
Definition
 Joules/sec.
Term
 Machine
Definition
 device that changes a force, make work easier, by changing size of force needed, the direction of a force, or distance over which a force acts
Term
 Work Input
Definition
 Input force x Input distanceWork done ON an object
Term
 Input ForceInput Distance
Definition
 Force exerted on a machineDistance the force acts through
Term
 Work Output
Definition
 Output force x Input forceWork done BY an objectcan't be changed unless work input changed or friction changed
Term
 Output forceOutput distance
Definition
 force exerted by a machinedistance output force is exerted through
Term
Definition
 number of times that a machine increases an input force
Term
Definition
 Output force/Input forcealways less than IMA cuz of friction
Term
Definition
 MA in absence of frictionInput distance/output distance
Term
 Efficiency
Definition
 Percentage of work input that become work output, always less than 100% cuz of frictionWork Output/Work Input x 100%
Term
 Lever
Definition
 rigid bar that is free to move around a fixed point
Term
 Fulcrum
Definition
 the fixed point a lever rotates around
Term
 Input arm
Definition
 distance between fulcrum and input force
Term
 Output arm
Definition
 distance between output force and fulcrum
Term
 IMA of a lever
Definition
 input arm/output arm
Term
 First Class levers
Definition
 Fulcrum in the middle, MA can be greater than/equal to/ or less than one
Term
 Second-Class levers
Definition
 Output force in the middleMA greater than one (output force > input)
Term
 3rd Class levers
Definition
 input force in the middleMA less than one (input > output force)
Term
 Wheel and axle
Definition
 two disks or cylinder, each with a different radiusScrewdriver: handle: input force and shaft: output
Term
 IMA of wheel and axle
Definition
 radius/diameter where input force is exerted (INPUT DISTANCE) DIVIDED bY radius/diameter where output force is exerted. if input distance>output, MA>1
Term
 Inclined planes
Definition
 slanted surface along which a force moves and object to a different elevation: steeper slope: more input force needed cuz input distance(trail) is greater than output distance(height)
Term
 IMA of inclined plane
Definition
 Distance along plane (input distance)/change in height (output distance)
Term
 Wedge
Definition
 V-shaped object whose sides are two inclined planes sloped toward each other
Term
 IMA of wedge
Definition
 thin wedge has greater IMA cuz less force needed to push it in, but doesnt do job as good (splitting wood)
Term
 Screw
Definition
 Inclined plane wrapped around a cylinder
Term
 IMA of a Screw
Definition
 Screw who has more threads moves forward less for each turn. greater IMA: closer threads- less force is needed
Term
 Pulley
Definition
 simple machine that consists of a rope that fits into a groove in a wheel, produce an output force different in size/direction/both from that of input force
Term
 IMA of a pulley
Definition
 number of rope sections supporting the load
Term
 Fixed Pulley
Definition
 wheel attached in fixed location, only able to rotate in place, direction of output force changed but force is not, IMA is always 1
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