View Factor Orientation (or View factor or shape factor) plays an important role in radiation heat transfer. View factor is defined as, "fraction of radiation leaving surface 'i' and strike 'j' ". Summation Rule (View Factor) If there is are similar surfaces 'i' and 'j' , then: Blackbody Radiation Exchange Radiation Exchange between Opaque, Diffuse, Gray surfaces in an Enclosure 1. Opaque 2. Surfaces 3. Two surface enclosure Radiation Shield It is used to protect surfaces from radiation act like a reflective surface. References: Material from Class Lectures + Book named Fundamentals of Heat and Mass Transfer by Theodore L. Bergman + My knowledge. Photoshoped pics are developed. Some pics and GIF from Google. Videos from YouTube ( Engineering Sights ).
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Planar Kinetics Of A Rigid Body: Force & Acceleration
The applied non-concurrent force system can cause the body to translate and rotate. The resistance of a body to angular acceleration is called Mass Moment of Inertia or simply Moment of Inertia ( M = Iษ ).
Mass moment of Inertia (MOI) is the integral of 2nd moment about any axis of all the element of mass 'dm'.
For e.g: flywheel of engine.
If the density of the body is not homogeneous, then you should use the following formula
Parallel Axis Theorem:
If the moment of inertia passing through its own axis, then moment of inertia about any parallel axis is given by using Parallel Axis Theorem.
Moment of inertia can be reported about a specified axis as radius of gyration.
And, the moment of inertia for different shapes but most important of these are disk and rod.
If composite body is given and moment of inertia is required, then you calculate MOI as:
Planar Kinetic Equations Of Motion:
There are two types of kinetic equations which are described ahead:
1. Force Equation or Translational Equation Of Motion:
Force equation for the center of rigid body states that: The sum of all the forces acting on the body is equal to the body's mass times the acceleration of its mass center 'G'.
So, applying equation of motion:
2. Moment Equation or Rotational Equation Of Motion:
This equation involves the effect the rotation of rigid body. Applying 2nd condition of equilibrium on above object, we get the final result as:
Where, Mp represents kinetic moment. There are conditions for kinetic moments which are:
If point P coincides with mass center G → In this case ๐ฅ̅ = ๐ฆ̅ = 0. So above equation becomes ∑๐๐บ =
๐ผ๐บ๐ผ.
If there is no rotation, only translation → In this case, angular acceleration becomes zero ( ฮฑ = 0 ), ∑๐p = ๐ฅ̅m(ap)x - ๐ฆ̅m(ap)y.
If there is both rotation and translation → In this case, the above equation remain as it was.
Equation Of Motion:
There are three cases for which equation of motion are to be defined:
There are two scenario along which analysis shall be completed and they are:
Considering mass center G as the starting point:
Considering point O as the starting point: (All equation remain the same however the Moment equation is changed as follows)
3. General Planar Motion:
This equation involves both translation and rotation.
References:
Material from Class Lectures + Book named Engineering Mechanics Statics & Dynamics by R.C. Hibbeler (12th Edition) + from YouTube channel named Yiheng Wang for Engineering Dynamics Mechanics + my knowledge.
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TAPING CORRECTIONS There are two types of corrections depending upon the type of errors in tape due to the different conditions. 1. Systematic Errors : Slope Erroneous tape length Temperature Tension Sag 2. Random Errors : Slope Alignment Marking & Plumbing Temperature Tension & Sag 1. Temperature Correction It is necessary to apply this correction, since the length of a tape is increased as its temperature is raised, and consequently, the measured distance is too small. It is given by the formula, C t = ๐ผ (T m – T o )L Where, C t = the correction for temperature, in m. ๐ผ = the coefficient of thermal expansion. T m = the mean temperature during measurement. T o = the temperature at which the tape is standardized. L = the measure length in m. For Foot Unit : C t = 6.45×10^-6 (T m – 68 )L For Metric Unit : C t = 1.16
ENGINEERING SURVEY Surveying is the science, art and technology of determine the relative positions of points above, on or beneath the Earth's surface so as to construct a map, plan or description. TYPES OF SURVEY : There are many types of survey but we discuss some of them. 1. Plane & Geodatic Survey : Ordinary field and topographical surveying in which the Curvature of Earth's surface is disregarded is called Plane Survey. It is performed when the area is smaller than 250sq.km. A survey of a large land area in which corrections are made for the Curvature of Earth's surface is called Geodatic survey. Why Geodatic Survey is important? Earth's surface is not flat, it is sphere. So all the calculations which were made by considering the Earth's surface flat are incorrect. So a new type of survey came into play which made calculations on the basis of geodatic condition of Earth's surface. 2. Topographic Survey : Topographic surv
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