Introduction/Design Specifications for Aircraft Stress amp; Strain A square rod of 200 mm, 1.5 m long, is pulled apart with a force of 50,000 N,

Introduction/Design Specifications for Aircraft

Stress & Strain

A square rod of 200 mm, 1.5 m long, is pulled apart with a force of 

50,000 N, what are the stress and strain?

 E = σ/ε 

• First, stress equals load divided by area. Area is 0.2 x 0.2 
• (units need to be in metres) 0.04 m2Metre
• Stress = 50,000/0.04 = 1,250,000 N/m2 1.25 MPa
• E = 210GPa
• Strain = stress/E  = 1,250,000/210,000,000,000 = 0.0000050
• The Elastic limit of steel 600MPa, this will not fail. 
• What load needed to reach yield?
• Ans 24,000,000 or 24MN

My question is how did he get the first dot ?

and how did they get the answer of 24,000,000