Unit 1 Topic 4: Solids Under Stress

Question 1

What is hooke’s Law?

Answer 1

Hooke’s Law states that F is proportional to extension provided that it’s within the elastic region

Question 2

What is the structure of rubber?

Answer 2

Rubber starts off coiled and as it gets unraveled it requires less force in order to get a great extension however once fully unraveled the force required increases as it’s molecules are now pulling away from each other

Question 3

What are crystalline materials give an example

Answer 3

The atoms within the material are arranged in an long-range ordered structure, with positive and negative ions forming a regular lattice. Examples would be metals.

Question 4

What are amorphous materials, give an example

Answer 4

Where the atoms are arranged in a short range non ordered structure and have rigid structures due to them being formed by directional covalent bonds locking atoms in place. Examples are glass and ceramics

Question 5

What are polymeric materials, give an example

Answer 5

Materials with long chain polymer molecules, most polymers are flexible and strong however the addition of cross-links will make them stiffer. Examples are rubber and plastics

Question 6

Explain dislocations

Answer 6

Breaks in bonds cause the bonds to be dislocated, they then slip depending on the direction of the force applied, this will cause the bonds to move until it reaches the edge which we then refer to as edge dislocation.

Question 7

How do you prevent these dislocations?

Answer 7

The addition of foreign atoms is a way of reducing dislocations as it will prohibit the slipping of bonds