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65 Cards in this Set
- Front
- Back
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product of force and distance
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work
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for a force to do work on an object, some of the force must act in the ____ -_____ as the object moves
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same direction
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no movement equals
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no work
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any part of a force that does not act in the same ____ of motion does ___ work on an object
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direction, no
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SI unit for work
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joule
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rate at doing work
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power
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doing work at a faster rate requires
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more power
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to increase the power you increase
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the amount of work done in a given time or you can do a given amount of work in less time
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formula for power
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power equals work/time force* distance/ time
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SI unit for power
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watt
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746 watts
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1 horsepower
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device that changes a force
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machine
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machines make work
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easier to do
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machines change
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size of a force needed, the direction of a force or the distance over which a force acts
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if you increase the distance you
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increase the force
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device that changes a force
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machine
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machines make work
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easier
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machines change_____
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size of a force needed, direction of a force or the distance over which a force acts
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some machines ____ the applie force but ____ the distance over which the force is exerted
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decrease/ increase
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because of ___ the work done by a machine is always ___ than the work done on the machine
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friction/ less
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force you exert on a machine
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input force
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distance the input force acts through
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input distance
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force exerted by the machine
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output force
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distance the output force is exerted
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output distance
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(output force)( output distane)
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work output
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number of times that the machine increases an input force
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mechanical advantage
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equals the ratio of the output force to the input
AMA= output force/ input force |
actual mechanical advantage
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mechanical advantage in the absense of friction
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ideal mechanical advantage
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because friction is always present, the __ ____ ____ of a machine is always less than the ideal
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sctual mechanical advantage
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formula for ideal mechanical advantage
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ideal= input distance/ output distance
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percentage of the work input that becomes work output
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effiency
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because there is always some friction the ___ of any machine is always less than 100%
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effiency
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six types of simple machines
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lever, wheel & axle, inclined plane, wedge, screw, pulley
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rigid bar that is free to move around a fixed point
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lever
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fixed point the bar rotates around
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fulcrum
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levers are classified into 3 categories based on
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the locations of the input force, output force adn the fulcrum
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distance between the input force and the fulcrum
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input arm
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distance between the output force and the fulcrum
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output arm
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to calculate the ideal mechanical advantage of any lever
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IMA=input arm/output arm
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fulcrum is always located between the input force and the output force
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1st class lever
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output force is located between the input force and the fulcrum
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2nd class lever
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input force is located between the fulcrum and the output force
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3rd class lever
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mechanical advantage can be greater than 1, equal to 1 or less than 1
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1st class lever
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mechanical advantage is always greater than 1
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2nd class lever
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mechanical advantage is always less than 1
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3rd class lever
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simple machine that consists of two disk/cylinders, each one with a different radius
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wheel and axle
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to calculate the ideal mechanical advantage of the wheel adn axle_____
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radius where the input force is exerted/ radius where the output force is exerted
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slanted surface along which a force moves an object to a different elevation
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inclined plane
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the ideal mechanical advantage of an inclined plane is the distance along the ______
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incline plane/ its change in height
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v-shaped object whose sides are two inclined planes sloped toward eachother
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wedge
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a thin wedge of a given length has a ___ IMA than a think wedge of the same length
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greater
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inclined plane wrapped around a cylinder
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screw
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screws with threads that are closer together have a ____ IMA
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greater
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simple machine that consists of a rope that fits into a groove in a wheel
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pulley
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the ideal mechanical advantage of a pulley/pulley system is equal to
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the number of rope sections
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wheel attached in a fixed location,
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fixed pulley
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attached to the object being moved
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movable pulley
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combined fixed and movable pulleys
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pulley system
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combination of two or more simple machines that operate together
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compound machine
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example of a compound machine
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watch
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reason james watt named the horsepower
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because horses were the most commonly used power in the 1700s
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output work is always ____ than the input work
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less
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materials engineers use to increase the mechanical advantage of a machine
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low-friction materials and lubricants
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screwdriver used to pry the lid off a paint can is an example of a
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1st class lever
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you pull easier if you have more
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MECHANICAL ADVANTAGE
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