3rd post

Hello we are eva and lidia and this is the third post

Stresses:  Are the physical demands that a body or object must withstand when one or more external forces are applied to it.
These are the basic stresses:

1-Compression : this is a caused by forces acting on a body that tend to flatten it or reduce its length or thickness.It happends in stuctures that need to support weigths.

2-Tenssion: this is caused by forces acting on a body that tend to strech it.

3-Bending: this is caused by forces acting on a element that make it curve or bend.It is done by suporting to the two ends and applying force in the centre as shown in tyhe figure to the right.

4-Torsion: this is caused by forces acting on a body that make it twist.

5-Shear: this is caused by two equal forces applied in opposite that act on lines of action close to each other.Shear stress will tend to cut the material if it cannot twist or bend

Pg 95 ex 12

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

Ballon : elastic 

Empty drinks can : plastic

Window frame : rigid

Clay : rigid

Catapult: elastic

Door : rigid