Review

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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.

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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.


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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.