المحاضره الخامسة

Question 1

the maxuim force first molar Occlusal surface, is about

Answer 1

650 N/mm²

Question 2

If the area of
contact is about 10 mm2, the force per unit area is then
nearly

Answer 2

65 N/mm²

Question 3

The jawbone is pivoted about a
socket jaw

Answer 3

in front of the auditory canal

Question 4

Formula of Bite force

Answer 4

M*mG/bN

Question 5

The mean value of Occlusal force ranged from ..
to
… N on the premolars, and from…
to …N on the
front teeth.

Answer 5

1-From 39 to 66N
2- from 11 to 33N

Question 6

Exmaple of tensile streets

Answer 6

Enamel :10 Mpa dentin: 106 Mpa amalgam: 32Mpa

Question 7

Examples of Compressive stress

Answer 7

Enamel: 384 M pa, dentin: 297 M pa, amalgam: 388M pa.

Question 8

Example of Shear stress

Answer 8

Enamel: 90 M pa, dentin: 138 M pa, amalgam: 188 M pa.

Question 9

where S is the shear bond strength, T is the tension applied, and A is the bonded area, the required bond
strength of orthodontic brackets ranges between

Answer 9

5.9 and 7.8 MPa.

Question 10

Newton’s first law

Answer 10

Newton’s first law essentially describes the concept of a body’s reaction (or resistance) to movement when acted upon by a force.

Question 11

Newton’s second law

Answer 11

The acceleration of a body is in the same direction as the force
that produces it

F net= m×a

Question 12

Newton’s thrid law

Answer 12

Newton’s third law states that with every action or
force, there is an equal reaction force (in the opposite
direction).

Question 13

Formula of systems of force

Answer 13

M = F × d