Learnamatrol Introduction to Levers- Applied Mechanisms Trainer

Mechanism

transmits mechanical force from one point to another

Basic mechanisms are combined to form

machines

Mechanisms are important

in modern industry and any career that works with machines

Lever

full beam that applies force by pivoting around a point

Lever examples

hammers, pry bars, scissors

Wheel

circular frame made of hard material capable of turning on an axis

Wheel examples

gears, sprockets, pulleys

Inclined planes

surface at an angle to the plane of the horizon

Inclined plane examples

boat ramps, threads on bolt or machine screw

Majority of industrial accidents occur due to

broken safety rules

Six safety rules

no loose apparel, keep safety devices in place, keep area clean, always turn off power when working on mechanical equipment, make sure people are clear and aware of equipment turning on

Force

something that acts on object by exerting either a push or a pull, has the ability to create motion or physical change in the object

Force expressed in

pund-force in US, newtons in Metric

Weight

force with which an object is attracted to Earth, also a measure of force

Weight is expressed in

pounds in US, newtons in metric

Mass

amount of matter contained within an object

Mass expressed in

slugs in US, grams or kilograms in metric

Calculate weight of object

weight=massxgravity

Hooke's law

distance an elastic material stretches or compresses from its original length depends on amount of force applied to it

Hooke's law useful when applied to

springs, a piece of metal or wire wound into a coil

Hooke's law formula

force=springratexdistancechanged

Spring scale

device that measures weight of object or force required to move it

Spring scale operation

weight applied to hook extends the spring, measure distance that spring extends

Lever advantages

amount of force generated is bigger than force applied

First-class lever

fulcrum between force and load

First-class lever examples

balance scale, see-saw

Second-class lever examples

nutcracker, bottle opener, wheelbarrow

Second-class lever

rigid beam that has load between fulcrum and force

Third-class lever

rigid beam that has force between fulcrum and load

Third-class lever examples

crane, serving tongs

Lever arm

rigid beam that mounts on fulcrum

Resistance arm

part of lever arm from fulcrum to point where load is located

Effort arm

part of lever from fulcrum to point where force is applied

First-class lever operatioin

force is applied on effort arm

Torque

force that makes an object rotate about a point

Torque aka

moment of force

Torque measured in

inch-pounds in US, newton-meters in metric

Torque formula

torque=forceappliedxdistancefromfulcrum

Rotational movement of a lever

when force on lever is large enough, rotational movement occurs

Law of moments

force needed to move load must create moment greater than moment created by load, and this force must act in the opposite direction

Law of moments formula

momentcausedbyeffortmoment>momentcausedbyresistancemoment

Calculate moment on a balanced lever

forceeffortxlengtheffort=forceresistancexlengthresistance

Mechanical advantage

name used to describe the ease of moving a particular force using a mechanism

Mechanical advantage formula in general

resistance force divided by effort force

Mechanical advantage formula for balanced lever

length of effort arm divided by length of resistance arm

FLE

force,load,effort

Third-class lever mechanical advantage will

never be greater than 1