2.1 LEVERS

A lever is a rigid bar that urns around a point called FULCRUM. Various forces may act on the lever at the same time.

Each force produces a specific torque.

                                           TORQUE = FORCE X DISTANCE 

Clases of levers

We can divide levers into three classes according with the position of the fulcrum, the force and the resistance.

Class 1:

The fulcrum is between the force and the resistance.

Class 2:

The resistance is between the fulcrum and the force.

Class 3:

The force is between the fulcrum and the ressistance.

Brake levers

We control bicycle levers to reduce speed, with levers on the handlebars.

A hand crack

A hand crack has two parts. One is conected to a rotating shaft and the other forms a handle. We can use it to apply force at a distance from the axis of the shaft.

Bicycle handlebars

The handlebrs of a bicycle work like a crank. If we place our hands at the ends of the handlebars, they are easier to turn.

1.2 CLASSIFICATION OF MECHANISMS, 1.3 CONSERVATION OF ENERGY AND WORK IN MECHANISMS

1.2. Classification of mechanisms

We can classify mechanisms by the work that they do and how they function.

-Transmition of motion.

-Transformation of motion.

-Motion control.

-Energy accumulation.

-Connection.

1.3. Conservation of energy and work in mechanisms.

 Mechanisms seem to increase force, but they can't create energy on their own. All mechanisms produce the same amount of work tht is done to them.

1.1. THE PARTS OF A MECHANISM

When you are riding a bike, your legs are the input motion, the pedals transmit the motion and the back wheel, the output receptor.

Input motion     →     Mechanism     →     Output force and motion    

Mechanism tranmit and trasform force and motion from an input force source (motor) to an output receptor. 

1. WHAT IS A MECHANISM?

The moving parts of a bicycle are examples of everyday mechanisms that make the lifes (our lifes) easier and funnier.

These mechanisms make work easier because they transmit and trasform force and motion.Mechanisms transmit motion and force to receptors that make the work.This is the output force and motion.

All these mechanism require an input force, mechanisms transmit motion and force to receptors and finally perform the work.

MECHANISMS

This entry is going to be to present the new unit that we are having lesson now.

The new unit is about mechanisms (like I have already said in the title), and it's going to consist of:

-1. What is a mechanism?

1.1. The parts of a mechanism. 

1.2. Classification of mechanism.

-2. Linear transmition of motion.

2.1. Levers.

2.2. Pulleys and compound pulleys systems.

-3. Rotary transmition.

3.1. Changes in speed.

3.2. Speed ratios.

3.3. Belt drives and gear trains.

3.4. Changes in direction and rotation.

5. CREATING INFORMATION

On the internet, we can quickly and easiliy create anything that we want. The most popular tools for doing it are web pages, blogs and wikis.

5.1. Web pages

Previously, tou have seen that a web page is a source of information. Now, you will learn about how to create attractive web pages, where you can share information with other people.

The first step is create and design the web page. The content must be interesting and visually, to attract more number of visits.

The steps that you must follow are.

1. Registrer a domain.

2. Sign up with a host server.

3. Design and create your web page.

4. Upload the web page to the server.

5. Update your web page regularly.

Domain names

To registrer a domain to the page, you must choose a name which isn't already being used.

Host servers

Some companies host web pages by offering space on their servers. Domain registration services may also provide hosting, and a web page design companies often include both, registration and hosting.

Designing and creating a web page

A website is a set of web pages under yhe same domain name.

Designing a web page

Thera are no official rules about how to doing t, howewer, you need basic knowledge of design, to insert images, change text colours...

Tittle

The tittle that you choose in your page is very important, cause it indicates what's the web page topic, and match your web page with other similar ones.

Colour combinations

Some web pages are quite difficult to read because their colour combinations are very poor. Your web page's colour combinaation has to be rich, fot people can 'enjoy' reading the web page.

Hyperlinks

Hyperlinks can be added to images or texts, and there are two types of them:

·External links take us to other websites related to the topic.

·Internal links take us to a different part of the sae web site.

Comment from other users

Although you shouldn't give any personal information on the Internet, it may be interesting to receive feedback from other people thet visit your web page, to now from outside about your blog.

Creating your web page

You have to create your web page following the next concepts:

1. Direct programming

Is the most difficult option, cause it requires knowledge. Divides into:

-HTML

-CSS

-PHP

-MySQL

2. Using a Content Management System (CMS)

We can use a CMS to create web pages.

These systems have several advantages:

a)They are fast.

b)Some are free.

c)Some services offer a package that includes hosting and CMS installation.

But, there are some disavantages:

a)You can't do anything that you want.

b)CMS programs take a long time to learn how to use them.

c)You must have a server with enough storage space for the program.

                                 

3. Using a web development program.

These programs 'translate' your web page design into HTML language. Some programs are: Kompozer, Web creator, etc.

        

4. Using the online hosting services that some pages offer:

This is the easiest way to create a web page. You only select the elements of your web page, and the program finish it with nomore information. Some examples are:

       

     

5.2. Blogs

Blogs are special type of web page, in wich the person which contains the blog (the blogger) goes updating content following the principal topic.

Blogs have other characteristics which made them more interesting:

-The same blog can be shared by different people.

-Blogs can include hyperlinks to other web pages.

Some of the most popular blogging services are Blogger, Wordpress and Tumblr.

 

5.3. Wikis

A wiki is a collection of web pages that visitors can edit, modify or expand. In this way, the content grows quickly with the contributions of people working on it.

The most popular examples of wikis are Wikispaces and PBWorks.