pag 92 ej 1,2
1) copy and complete the following table in your notebook :
TYPES OF STRUCTURES
|
EXAMPLES
|
MASS
|
WALLS,DAMS,ETC.
|
FRAME
|
SPIDER WEB, BYCICLE,ETC.
|
TRUSS
|
ROOFING,BRIDGES,ETC.
|
SUSPENDED
|
TENTS,MARQUEES,ETC.
|
2) Have you ever seen a structure that used cables? Write down the names of the ones that you can remenber or the ones that you can see and draw them in your notebook.
wire bridge
pag 93 ej 3,6
3) When a person sits on a chair, the stress that the chair has to withstand is due to the weigth of the person, whereas the strenght is the chair´s ability to withstand the load without breaking. Indicate which is the stress in these two exaples:
a) A wardrobe hanging from a rope.
Stress because it have more than two forces
b) A twisting telephone cord.
Strength because it have external forces without breaking.
6) Describe the structure of a turtle´s shell. Why do you think it has this shape? what material do you think it is made from? Is it strong enough for the stresses it has to withstand?
For cover all his body.
its is made with plaque bone.
yes is enought
pag94 ej 7,9
7)
a rope with a weight hanging off it . stress
a man pushing a cabinet . no stress
tightening a screw. no stress
cutting our fingernails. stress
9)
a table is a rigid object because it no braked.
