martes, 8 de abril de 2014

SOLAR POWER PLANTS

These plants use the energy from the sun. There are two main types of installations: photo-thermal and photovoltaic power plants.

Photo-thermal power plant

In this type of power plant, the heat generated by solar radiation produces steam that is used to move the rotor in the generator.

To do this, they use special mirrors, called heliostats,  that reflect sunlight and concentrate it at one point, where it reaches a high temperature.

https://www.youtube.com/watch?v=NDZzAIcCQLQ


Photovoltaic power plant

In these power plants, solar radiation is transformed directly into electricity by panels of photovoltaic cells.
These power plants consist of large areas of photovoltaic panels.

jueves, 6 de marzo de 2014

RESISTANT ELEMENTS IN STRUCTURES

VERTICAL
PILLAR: a larg post that helps to holp up something (roof  or building)


COLUMN:  a long post made of steel, stone, marble, etc., that is used as a support in a building

HORIZONTAL


BEAM:  a long piece of heavy often squared timber suitable for use in buildings.


JOIST: small beam.


FOUNDATION

FOOTING:  an elargement at the lower end of a foundation in a wall, pier or column to distribute the load.

SLAB: a flat rectangular architectural element that is usually formed of a single piece of mass: concrete.


WRITE THE NAME OF THE FOLLOWING ELEMENTS

1. 

2.

3.

4.

5.

6.

7.





miércoles, 5 de marzo de 2014

PULLEY

1. FIX PULLEY

A fixed pulley is a wheel that has a groove around it into which a rope, chain or belt fits. It rotates around an axle that is fixed to an inmobile surface.

A fixed pulley is ballanced when the effort F is equal to the resistance of the load, R:




       F=R

2. MOVABLE PULLEY

A movable pulley is a set of two pulleys- one is fixed while the other can move in a linear direction.

A movable pulley is balanced when it satisfies this equation:
       
            R
F = -----
        2

3. COMPOUND PULLEY

This is a system of fixed and movable pulley, often called block and tackle.

        R
F=--------
       2n
n= number of movable pulleys.



lunes, 24 de febrero de 2014

SIMPLE MACHINES


Click on the following links to watch  the videos.

Three classes of levers

Types of levers




Exercise

Sammy weighs 9000 kg and Jane weighs 6000 kg. They are both sitting on a seesaw. If

Sammy is seated 6 meters away from the fulcrum, how far should Jane be from the fulcrum?. When solving the problems, draw a diagram of the situation and show your math work.

jueves, 20 de febrero de 2014

WOOD- ACTIVITIES

COMPLETE THE FOLLOWING ACTIVITIES:

1. What are the two main substances that wood is composed of?

2. If we cut a tree, in the cross section we can see these different five parts. Write  and draw them.

3. - The .................. are the lines in pieces of wood.
    - A ...................... is the main part of the tree without branches after cutting it.
    - The ...................... is the part  that protects the tree from wind, rain, insects, etc.
    - A ....................... is a small branch.
    - The singular of leave is ..................


4. True or false?
         - Wood is denser than water.
         - Wood is a good thermal insulator.
         - Wood is a good electric conductor.
         - Wood is not a biodegradable material.

5. Write the seven steps to process wood (from cutting the tree to plane it).

6. Write three characteristics of hardwood and  three of softwood.

7. Write four examples of hardwood and four of softwood.

8. What are the four types of prefabricated wood products?
     

miércoles, 19 de febrero de 2014

HOW TO PROCESS WOOD

The process starts with the extraction of the log (raw material) from the forest and ends with the production of planks.

STEPS

1. Cutting
2. Pruning
3. Transport
4. Removing the bark
5. Sawing
6. Drying
7. Planing

martes, 18 de febrero de 2014

HARDWOOD Vs SOFTWOOD



HARDWOOD
SOFTWOOD
DEFINITION
Comes from deciduous trees that drop their leaves every year.
Conifer trees have needles, normally do not lose them. Evergreen
EXAMPLES
Examples of hardwood are  teak, walnut, oak, ash, elm, poplar, birch, maple etc.
Examples of softwood trees are pine, spruce, cedar, fir, larch, etc.
COST
Hardwood is typically more expensive than softwood.
Softwood is typically less expensive compared to hardwood.
GROWTH
Hardwood has a slower growth rate.
Softwood has a faster rate of growth.
CHARACTERISTICS
Wide, round crown. Leaves are broad. Its fruit may be: nut, chesnut and berries.
Straight, slender. The crown is narrow. The leaf is a needle. The fruit is a  cone
COLOR
Dark
Light
STRUCTURE
Non - resinous and close grained
Resinous

CLASSIFICATION OF MECHANISMS

A. TRANSMITTING MOTION.

                    - Linear: Lever, Fixed pulley, Movable pulley, Compound pulley.
                    - Rotary: Friction drives, Pulleys with belt, Gear mechanisms, Worm gear, etc.

B. TRANSFORMING MOTION.

                    - Rotary to Linear: Rack and pinion system, Nut and bolt system, Winch and crank handle
                    - Rotary to Reciprocating: Crank-link-slider, Crankshaft, Cam, Eccentric cam

C. CONTROLLING AND REGULATING MOTION.

                   - Disc brakes.
                   - Band brakes.
                   - Drum brakes.

D. STORING ENERGY.

                   - Spring.

E. JOINING ELEMENTS.

                  - Clutch.
                  - Fixed connections.
                  - Movable connections.


EXERCISE : Choose at least three mechanisms and describe them. Include diagrams, pictures, formulas, real applications, etc.You have to do each machine in a single worksheet. 
 It´s not compulsatory. If you do it you can add 0.25 to the final mark of the revision test.






DEFINITION OF MECHANISM

Mechanisms are devices that transmit and convert forces and motion from a driving force or input element to an output element.
They allow us to carry out certain tasks more easily and more efficiently.

lunes, 17 de febrero de 2014

UNIT 8. MECHANISMS.

VOCABULARY

TRANSLATE INTO SPANISH

Inclined plane
Wheel
Axle
Lever
Pulley
screw
wedge
force
speed
ramp
motion
frictionless
pivoting point
 fulcrum
lever
arm,
moment of force
Examples of levers: wheelbarrow, fishing rod, scissors, hole punch,
broom, pincers, scales, tongs, nutcracker, pliers,
fire extinguisher, handle, paper cutter, tweezers,
crowbar, shovel, can opener, stapler, brake, oar, bottle opener,steering wheel,
windlass, coffee grinder, pepper mill, water tap, crane, flag pole, fixed, movable,