Exercises page 131

1)🌟 Define these concepts: power source, conductor, load device. Give an example of each.



Power source: a power source is a source of power. Most commonly the type of power referred to is:

• Power (physics), the rate of doing work; equivalent to an amount of energy consumed per unit time
• Electric power, the rate at which electrical energy is transferred by an electric circuit; usually produced by electric generators or batteries

Conductor: an object, substance or material allowing the flow of an electric charge.

Load device:  A unit load device (ULD) is a pallet or container used to load luggage, freight, and mail on wide-body aircraft and specific narrow-body aircraft.






2)🌟 List all the control and protection devices that you can think of and explain what they do.

One-way switch: Open or close the circuit when they are actuated.
Push switch: Open or close the circuit, but only while we keep them pressed.
Two-way switch: Open and close one or more circuits. They can also open some circuits and close others ones simultaneously.
Limit switch: Functions as a switch toggles between two positions when it is operate by a lever.
Fuse: Protect the components of electric circuits from power surges.


3)🌟 Which materials are used to make an electric wire (inside and out)?


 Wires are made of copper (inside) and of plastic casing (outside).


4)  We know that the circuit in the figure below is equivalent circuit of two identical resistor connected in series, that the cell is 9V and that the current flowing through the circuits is 0.3mA.

a) Calculate the value of the equivalent resistor.

R= V / I > 9/0.3 = 30Ω
b) Calculate the value of the resistors in the initial circuit.


c)  Draw the initial circuit.

💡⌁💡Electric Circuits💡⌁💡

This work has been done by Lucía and I in her technology blog:
http://technology2apl.blogspot.com.es/2017/06/

Leonardo Digitale

[Figure 1]

This weight lifting tool has a worm that engages many wheel spindles with its turns, for that reason it is very safe. In contrast, when the screw engages a single wheel tooth that withstands all the effort, if that tooth breaks, it could cause serious damage and prejudice.

[Figure 2]

a B C D E

I argue that if a flat surface weight is to move on another plane of solid surface, its movement will facilitate, whether they are interposed between them balls or if you use rollers. Between balls and rollers I see no other difference except that the balls have a universal movement, in all directions, while the rollers can move in only one direction.

However, if the balls or the rollers touch each other as they move, there is no doubt that the movement will be more difficult than if such contact does not exist, since their contacts are produced by opposing movements, as in the 5th of the sixth Is demonstrated and, consequently, such friction causes contrary movements.

But, if the balls or, if we mean, the rollers are kept at a certain distance between each other, there will be no more contact between weight and resistance than a single point, as shown in the penultimate of the second, and for that reason it is as if both planes were held at the ends of the line of support and, consequently , It will be easy to make such a move.

[Figure 1]
If the pinion is the one that moves the wheel, the spaces between the teeth of the pinion should be larger than those of the wheel. If the wheel is the one that moves the pinion, it would do the opposite.However, if both are well made, it is acceptable that they have equal spaces and teeth.

[Figure 2]
If you turn one of these wheels, the other, being united, will turn in the opposite direction

[Figure 3]
If you want a wheel to rotate in the same direction as the driving wheel, that wheel must have a third degree movement.

[Figure]
[Figure 4]
A b c d
Whichever direction you turn the wheel d, the wheels a b will rotate in it. And the wheel c will turn in the opposite direction. The same will happen when turning a and b. And if you turn the wheel c, all the others will turn the opposite.

[Figure]
[Figure 5]
If you put two wheels spinning one to the other with your teeth, if they are in contact from outside, the wheels will turn in the opposite direction. But if one of the wheels with its outer teeth turns the other through the inner part, the wheels will rotate in the same direction, either of the two drive wheels.

Classification of motion mechanisms

Crank and slider, Chain and sprocket systems and ratchatet ( By Lucía Horcajo)


http://technology2apl.blogspot.com.es/2017/04/mechanisms.html



Belt and pulley system, Screw and nut and Wedge ( By Andrea Caballero)



http://andreastechnologynotebook.blogspot.com.es/2017/05/mechanisms-workshits.html


Gears, Rack and pinnion and Ramp ( By Sara García)

Machines and mechanisms translations

• Linear motion- Mmovimiento lineal

• Rotatory motion- Movimiento rotatorio

•  Reciprocating motion- movimiento recíproco

• Oscilatig motion-  Movimiento oscilante 

• Motion transmission mechanisms- Mecanismos de transicion de movimiento

• Motion conversion mechanisms- Mecanismos de conversion de movimiento

• Crowbar- Palanca

 

• See-saw- Balancín

 

• Pliers- Alicates

 

• Scissors-Tijeras

 

• Oar- Remos
•  
• Nutcrackers- Cascanueces
•  
• Wheelbarrows- Carretillas
•  
• Paper punch- Perforadora de papel
•  
• Tweezers- Pinzas
•  
• Kitchen tongues- Lenguas de cocina
•  
• Staple removers- Quitagrapas
•  

Review

Page 92

1) Copy and complete the following table in your ntebook:

Types of structures:                                                              Examples:

• Mass                                                                           Walls, dams, etc.
• Frame                                                                         Structure of a building
• Truss                                                                           Cranes, electricity pyloms, etc.
• Suspended                                                                   Bridges, tents, marquees, etc.

2) Have you ever seen an structure that uses cables? Write down the names of the ones that you can remember or the ones that you can see and add a picture. 

Yes, the Madrid Cable Car.

3) When a person sits on a chair, the stress that the chair has to withstand is due to the way of the person whereas the strength is the chair´s ability withstand the load without braking. Indicate which is the strength and which is the stress in these two examples:
a) a wardrove hanging from a rope: the stress is the rope and the strength is the wardrove.
b) a twisting teephone cord: the stress is the phone cord and the strength is the phone.

Page 94


7) Which types of stress do the following elements and activities have to support: a rope with a weight hanging of it, a man pushing a cabinet, tightening a screw, cutting or fingernails.

1)Tension
2)Compresion
3)Compresion (but there is a twisting movement)
4) Shear


9) Write a short description of three objects using one of the following adjetives for each object: rigid, elastic and plastic. Explain how these properties allow the objects to fulfil their functions or make them suitable for their purpose.


 A wall is rigid because if you try to pull it or bend it, you can´t.
 An elastic band is elastic because when you strech  it, it deforms but it comes to its original place.
A water bottle is plastic because it is made of that material.


Page 95


11) Copy and complete the following table.


Object                                                                                            Properties

Brick                                                                                               Rigid
Slime                                                                                               Deformable
Elastic band                                                                                     Elastic
Water bottle                                                                                     Plastic 



12) Thk about the following objects and state whether they are rigid, plastic or elastic: balloon, empty drinks can, window frame, clay, catapult, door.

Rigid: window frame, catapult, door.
Plastic: empty drinks can.
Elastic: balloon, clay. 

Structures

These are two examples of structures:

Mass structures: These are solid, heavy and very sturdy structures. Examples include walls, dams, etc.

Suspended structures: These are held in place by cables and suspenders attached to sturdy supports. Examples include suspensión bridges, tents, marquees, etc.