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BSC : Mechanical engineering

Bsc Page one lectures

How to calculate stress in objects ?

Stress = Load /Area

1000×98.1/100×10*-6

= 98.1 MN/M2

10-6 changes the units into metro

1,000,000mm2 is 1m2

Mass x gravity

Cross section

Force = Mass X Acceleration

Strain = Change in length

Measuring Stress and Strain

Hookey Law

In elastic range of a material “the extension is proportional to force”

ie Stress = E* Strain

Young modules = Stress/Strain

Class exercise

  1. A 3mm diameter steel wire supporting a mass 50kg ?

    What is the tension in the wire?

    9.81 x 50 = Tension

Tension

T=Force= MxA=1.5 x 3.14

Tension = 50 x 9.81 Newtons

Tension = 490.5 Newtons

Strain

E = Stress / Strain

Strain = Stress/E

Structures

Structures sharing the load ,main aim to combine different materials to reduce the amount of material used .

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