If the specific surface energy for soda–lime glass is 0.30 J/m2 and its modulus of elasticity is (69 GPa), compute the critical stress required for the propagation of an internal crack of length 0.8 mm.

the critical stress for the sodalime glass = 5.7MPa

Explanation:

Ist Step

we Calculate  half length   of internal crack as

2a =0.8 mm

a = 0.8/2 = 0.4 mm

Changing  to meters becomes = 0.4 / 1000 =0.0004m

2nd Step

Now  the critical stress required for the propagation of the internal crack can be calculated using the formulae

Critical Stress (σc) =      (2 E γs/ πa) 1/2

where E= modulus of elasticity

γs= specific surface energy for soda–lime glass

a= Length

= (2 x 69 x 10 ^9 x 0.30/ π x 0.0004)1/2

=

= 5,739,407.8= 5.7 x 10^6 N/m^2

= 5.7MPa

it was a fall down when it happens

explanation: