# 0.3 Simple machine elements  (Page 2/3)

 Page 2 / 3

As shown in , there are three different classes of levers defined by the relativepositions of the fulcrum, effort, and load. A first class lever has the fulcrum positioned between the effort and the load. Examples of first class levers include: abalance, a crow bar, and scissors. In a second class lever the load is placed between the fulcrum and the effort. Examples of second class levers include: awheelbarrow, a bottle opener, and a nutcracker. Third class levers place the effort between the fulcrum and the load. Examples of a third class lever are a hammer, afishing rod, and tweezers. Most machines that employ levers use a combination of several levers, often of differentclasses.

## The wheel and axle

Both levers and the inclined plane lower the force required for a task at the price of having to apply that force over a longer distance. With wheels andaxles the same is true: a poweful force and movement of the axle is converted to a greater movement, but less force, at the circumference of the wheel. In a circular geometry, torque is a more useful concept than force and distance. You can learn more about torque here . The wheel and axle can be thought of as simply a circular lever, as shown in . Many common items rely on the wheel and axle such as the screwdriver, thesteering wheel, the wrench, and the faucet.

## Gears and belts

A wheel and axle assembly becomes especially useful when combined with gears and belts. Gears can be used to change the direction or speed of movement, but changing the speed ofrotation inversely affects the force transmitted. A small gear meshed with a larger gear will turn faster, but withless force. There are four basic types of gears: spur gears, rack and pinion gears, bevel gears, and worm gears. Spur gears are probably the type of gear thatmost people picture when they hear the word. The two wheels are in the same plane (the axles are parallel). With rack and pinion gears there is one wheel and one rack, a flat toothed bar that converts the rotary motioninto linear motion. Bevel gears are also known as pinion and crown or pinion and ring gears. In bevelgears, two wheels intermesh at an angle changing the direction of rotation (the axles are not parallel); thespeed and force may also be modified, if desired. Worm gears involve one wheel gear (a pinion) and one shaft with a screw thread wrapped around it. Wormgears change the direction of motion as well as the speed and force. Belts work in the same manner as spur gears except that they do not change the direction ofmotion.

In both gears and belts, the speed and force is altered by the size of the two interactingwheels. In any pair, the bigger wheel always rotates more slowly, but with more force. On both the big and the small gear, the linearvelocity at the point of contact for the wheels is equal. If it was unequal and one gear were spinning faster than theother at the point of contact then it would rip the teeth right off of the other gear. As the circumference of thelarger gear is greater, a point on the outside of the larger gear must cover a greater distance than a point on thesmaller gear to complete a revolution. Therefore the smaller gear must complete more revolutions than the larger gear inthe same time span. (It's rotating more quickly.)

how can chip be made from sand
is this allso about nanoscale material
Almas
are nano particles real
yeah
Joseph
Hello, if I study Physics teacher in bachelor, can I study Nanotechnology in master?
no can't
Lohitha
where is the latest information on a no technology how can I find it
William
currently
William
where we get a research paper on Nano chemistry....?
nanopartical of organic/inorganic / physical chemistry , pdf / thesis / review
Ali
what are the products of Nano chemistry?
There are lots of products of nano chemistry... Like nano coatings.....carbon fiber.. And lots of others..
learn
Even nanotechnology is pretty much all about chemistry... Its the chemistry on quantum or atomic level
learn
da
no nanotechnology is also a part of physics and maths it requires angle formulas and some pressure regarding concepts
Bhagvanji
hey
Giriraj
Preparation and Applications of Nanomaterial for Drug Delivery
revolt
da
Application of nanotechnology in medicine
has a lot of application modern world
Kamaluddeen
yes
narayan
what is variations in raman spectra for nanomaterials
ya I also want to know the raman spectra
Bhagvanji
I only see partial conversation and what's the question here!
what about nanotechnology for water purification
please someone correct me if I'm wrong but I think one can use nanoparticles, specially silver nanoparticles for water treatment.
Damian
yes that's correct
Professor
I think
Professor
Nasa has use it in the 60's, copper as water purification in the moon travel.
Alexandre
nanocopper obvius
Alexandre
what is the stm
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
Rafiq
industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
Damian
How we are making nano material?
what is a peer
What is meant by 'nano scale'?
What is STMs full form?
LITNING
scanning tunneling microscope
Sahil
how nano science is used for hydrophobicity
Santosh
Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
Rafiq
what is differents between GO and RGO?
Mahi
what is simplest way to understand the applications of nano robots used to detect the cancer affected cell of human body.? How this robot is carried to required site of body cell.? what will be the carrier material and how can be detected that correct delivery of drug is done Rafiq
Rafiq
if virus is killing to make ARTIFICIAL DNA OF GRAPHENE FOR KILLED THE VIRUS .THIS IS OUR ASSUMPTION
Anam
analytical skills graphene is prepared to kill any type viruses .
Anam
Any one who tell me about Preparation and application of Nanomaterial for drug Delivery
Hafiz
what is Nano technology ?
write examples of Nano molecule?
Bob
The nanotechnology is as new science, to scale nanometric
brayan
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Damian
Got questions? Join the online conversation and get instant answers!