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 ).
If force acting on the body result in some traveled distance, then it is called work.
So, the formula for work done is given by:
The above formula can be written as:
There are three types of work which are described below:
Positive Work → If the angle between force and displacement is acute (0 < θ < 90).
Negative Work → If the angle between force and displacement is obtuse (90 < θ < 180).
Zero Work → If the angle between force and displacement is right (θ = 90).
Work Done By Variable Force:
If there is no constant force applied on an object for work done. The formula for work done by variable force is given by:
Work Done By Constant Force:
If constant force is applied on an object to displace from one point to other point but keep in mind it should be in a straight line. The formula for work done by constant force is given by:
Work Done By Weight:
The work done by an object having weight 'W' moving from 's1' to 's2' under the action of gravity is given by:
Work Done By Spring Force:
If we apply force on spring then it is elongated or compressed by a small distance 'ds'. The work done by the force on the spring in moving it from unstretched position to new final position is given by:
Applying 2nd equation of motion Ft = mat with at = v dv/ds, we get:
Since we know T = 0.5 x mass x square of velocity, so
Principle Of Work & Energy For System of Particles:
Principe of work and energy is applied on:
Enclosed region of space.
Work for which internal forces is zero.
For the system of particles, the principle of work and energy is given by:
There should be no energy loss due to particle interaction.
If there is energy loss → this equation cannot be used.
Types of Forces:
There are two types of forces which are described ahead:
Conservative Forces → If the work done by a force is independent of path followed, then it is called Conservative Forces. For e.g: weight, spring force, etc.
Non-Conservative Forces → Forces for which work done around a path is not zero and is dependent of path followed. For e.g: frictional force, etc.
Gravitational Potential Energy:
Energy due to height is called gravitational potential energy. This energy is given by:
Elastic Potential Energy:
The elastic potential energy (due to compression or elongation of spring) is given by:
Potential Function:
Potential function is the sum of gravitational and elastic potential energy. Its formula is given by:
Conservation of energy means: "Total energy of the system of particles remains constant if only the conservative forces doing work to the system".
Since, considering the work done by non-conservative energy is zero. So:
For the system of particles:
First we will learn statics and dynamics and then we will talk about why we need to learn these?
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.
It depends on the scenario when and what equation to use. If there is a force acting on a body and displacement is shown then energy and work principle should be used. If there is a vertical displacement or no contact with horizontal during motion then use energy conservation. ******************************* For momentum and impulse equation: If there are non-conservative and conservative forces bith are present between bodies then use Impulse (Linear or Angular) and momentum principle. If there is only conservative forces present then use momentum conservation. Hope you will find your question's answer.
Introduction To Structural OR Concrete Design Beams must have adequate strength against different types of failure which are: Shear more dangerous than Flexural (or Bending) failure because it creates additional tensile stresses. E.g.: Airplane wing (act as cantilever beam ) and made of Nanocomposites, composites, aluminum. Following are the types of failures in Beam: Flexural (or bending) failure Diagonal Tension failure Shear-Tension failure Shear-Compression failure Following are the types of Shear : Longitudinal Shear Transverse Shear Shear Failure Diagonal Tension Failure ↠ Shear failure of reinforced concrete beam (difficult to predict). Only valid for Homogenous beams . When we apply load on beam ↠ Bending as well as Shear stresses are produced. Shear stress have maximum value at Neutral axis N.A. Bending stress have maximum value at Extreme fibers. At maximum bending stress ↠ shear stress = 0 . Assumptions for shear stresses i...
Strain Energy or Resilence It is defined as, " energy absorbed in a body when deformation is done on material " . Depend on Material . Strain Energy Density is defined as, " strain energy per unit volume " . Independent of material . Used to tell which deformation component is greater with direction. If greater in specific direction ↔ crack propagates in that direction. Stress (in Dynamic effect) > Stress (in Static effect) Types of Loading Energy Conservation It states that, " Energy can neither be created nor be destroyed but can transfer in other forms " . We only deal with mechanical energy. External work = internal energy or strain energy . If this external force is in elastic limit, strain energy restores body back to its original undeformed position. Note: For Castigliano's Theorem ↔ See Energy Method . With the application of force on Car chassis , How it behaves? References: Material from Class Lectures + Book named Engineering Mec...
Gear Generation by Machining Tooth profile is provided by much simpler form cutting tool through hobbing, gear shaping. It involves the following methods: Gear Hobbing Gear Shaping 1. Gear Hobbing It is defined as, " a machining process in which gear teeth are progressively generated by a series of cuts with a helical cutting tool " . Most accurate machining process. Used for gears production because it has excellent surface finish. Continuous Indexing Process ↠ in which both cutting tool and workpiece rotate in constant relationship while hob is being fed into work. Feed Directions The direction of feed during hobbing operation depends upon the type of gear to be cut. Following are the types of feed directions: Axial Feeding ↠ cutting spur and helical gears (Hob axis is parallel to Blank axis). Radial Feeding ↠ for bevel gears (Hob axis is perpendicular to Blank axis). Tangential Feeding ↠ for worm, straight, spiral...
When did i use conservation of energy and when i use principle of work and energy? I mean at what scenario?
ReplyDeleteIt depends on the scenario when and what equation to use.
ReplyDeleteIf there is a force acting on a body and displacement is shown then energy and work principle should be used.
If there is a vertical displacement or no contact with horizontal during motion then use energy conservation.
*******************************
For momentum and impulse equation:
If there are non-conservative and conservative forces bith are present between bodies then use Impulse (Linear or Angular) and momentum principle.
If there is only conservative forces present then use momentum conservation.
Hope you will find your question's answer.