In casting experiments performed using a certain alloy and type of sand mold, it took 170 sec for a cube-shaped casting to solid
2 answers:
Answer:
a) the value of the mold constant in Chvorinov`s rule is 2.45 s/mm²
b) the total solidification time is 170 s
Explanation:
a) The volume is 50³ = 125000 mm³
The area is
A = 6 * 50² = 15000 mm²
The ratio V/A is
125000/15000 = 8.33 mm
The mold constant in Chvorinov`s rule is
b) The volume is
The area is
V/A = 98174.8/11781 = 8.33
The total solidification is
T =2.45 * (8.33²) = 170 s
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Answer:
b). False
Explanation:
Lumped body analysis :
Lumped body analysis states that some bodies during heat transfer process remains uniform at all times. The temperature of these bodies is a function of temperature only. Therefor the heat transfer analysis based on such idea is called lumped body analysis.
Biot number is a dimensionless number which governs the heat transfer rate for a lumped body. Biot number is defined as the ratio of the convection transfer at the surface of the body to the conduction inside the body. the temperature difference will be uniform only when the Biot number is nearly equal to zero.
The lumped body analysis assumes that there exists a uniform temperature distribution within the body. This means that the conduction heat resistance should be zero. Thus the lumped body analysis is exact when biot number is zero.
In general it is assume that for a lumped body analysis, Biot number 0.1
Therefore, the smaller the Biot number, the more exact is the lumped system analysis.
Answer:
Explanation:
Heat engine
Heat engine is a device which produce work while consuming some amount of energy .This engine works in cycle.In other words we can say that Heat engine is a device which covert thermal or chemical energy in to mechanical energy and after that this mechanical energy can be use for producing mechanical work.
Heat engine takes heat from high temperature and rejects heat to lower temperature and producing work.
We know that efficiency given as
From diagram we can say that
So efficiency
The question is incomplete. The complete question is :
The solid rod shown is fixed to a wall, and a torque T = 85N?m is applied to the end of the rod. The diameter of the rod is 46mm .
When the rod is circular, radial lines remain straight and sections perpendicular to the axis do not warp. In this case, the strains vary linearly along radial lines. Within the proportional limit, the stress also varies linearly along radial lines. If point A is located 12 mm from the center of the rod, what is the magnitude of the shear stress at that point?
Solution :
Given data :
Diameter of the rod : 46 mm
Torque, T = 85 Nm
The polar moment of inertia of the shaft is given by :
J = 207.6
So the shear stress at point A is :
Therefore, the magnitude of the shear stress at point A is 4913.29 MPa.