A glass plate is subjected to a tensile stress of 40 MPa. If the specific surface energy is 0.3 J/m2 and the modulus of elastici
1 answer:
Answer:
The maximum length of a surface flaw is 8.24 μm
8.24 μm
Explanation:
Given that:
The modulus of elasticity E = 69 GPa
The specific surface energy = 0.3 J/m²
The length of the surface flaw "a" = ??
From the theory of the brittle fracture;
Making a the subject of the formula; we have:
a = 8.24 × 10⁻⁶ m
a = 8.24 μm
Thus; the maximum length of a surface flaw is 8.24 μm
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Answer:
γ =0.01, P=248 kN
Explanation:
Given Data:
displacement = 2mm ;
height = 200mm ;
l = 400mm ;
w = 100 ;
G = 620 MPa = 620 N//mm²; 1MPa = 1N//mm²
a. Average Shear Strain:
The average shear strain can be determined by dividing the total displacement of plate by height
γ = displacement / total height
= 2/200 = 0.01
b. Force P on upper plate:
Now, as we know that force per unit area equals to stress
τ = P/A
Also, τ = Gγ
By comapring both equations, we get
P/A = Gγ ------------ eq(1)
First we need to calculate total area,
A = l*w = 400 * 100= 4*10^4mm²
By putting the values in equation 1, we get
P/40000 = 620 * 0.01
P = 248000 N or 2.48 *10^5 N or 248 kN
Answer:
The electric field to balance the weight is approximately equals to 3.49x10^5 Newton/Coulumb
Explanation:
In order to be stationary position, magnitude of the total force due to electric field should be equal to the gravitational force that is,
where
where <em>q</em> is the charge of the droplet and E is the electric field. On the other hand
where <em>m</em>,<em>V ,d</em> and<em> r</em> are the mass, volume, density and radius of the oil droplet respectively and <em>g </em>is the gravitational acceleration (g=9,80665 m/sn^2). By using the first equation and solving it for the electric field we can write,
(Note: d=0.85 x 10^-3 kg/cm^3 and the unit of electric field is Newton per coulumb (N/C))