exercises unit 5 and vocabulry

    Exercises unit 5

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• PAGE 93:3,6
• PAGE94:7,9
• PAGE95:11,12 

1.- Copy and complete the following table in your nootebook.

Types of structures	Examples
Mass	Walls,dams…
Frame	Schools,houses …
Truss	Cranes,electricity pylons…
Suspended	Tents,maerquees…

2.-Have you ever seen a structure that uses cables?Write down the names of the ones that you can remember or the ones that you can see and draw them in your notebook.    Electricity pylons  

3.- when a person sits on a chair,the stress that the chair has to withstand is due to the weighth of the person whereas the strength is the chair´s ability to withstand the load with out breaking.Indicate wich is the sterngth and which is the stress in the examples:

a) A wardrobe hanging from a rope :stress
b) A twisting telephone cord: sterngth

6.- Describe the estructure of a turtle´s shell .Why do you think it has this shape?what material do you think its made from?
is it strongenough for the stesses it has to withstand?
The shell of a turtleis form by an hexagon structures.
I think it has that shape to resist big forces.

7.- Which types of stress do the folowing elements and activities have to support :a rope with a weight hanging of it( tension )
man pushing a cabinet(compression)thightening a screw(tension) cuting our fingernails(shear).

9.- Write a short description of three objets using one of the follwing adjetives for each objects: rigid,elastic and plastic.

Wood table :rigid  Elastic band :elastic   Plastic bottle:plastic

11.- Copy and complete the following table in your notebook with objects that have the properties shown in the right-hand column.

objects	properties
brick	Rigid
Clay	Deformable
Rubber	Elastic
Chewing gum	Plastic

12.-Think about the following objects and state whether they are rigid ,plastic or elastic:

• empty drink can(plastic)
•  ballon(elastic)
• window frame(rigid)
• clay(plastic)
• catapult(elastic/rigid) 
• door(rigid)

 VOCABULARY

Driver element: elemento conductor

Driven element:elemento conducido: elemento de conversion y/o transmision

Linear motion: movimiento linear

Rotary