Subject: Engineering Mechanics Subject Code: BE2104 1st Semester: Applicable Branch (es): ALL Question Code: G558 Year of Examination: 2014 Exam Type: (Special/Regular): 1st year special examination - 2014 Solution Prepared by Sl.No. Faculty Name Email ID 1 Aswini Kumar Khuntia email@example.com 2 3 4 NATIONAL INSTITUTE OF SCIENCE &TECHNOLOGY PALUR HILLS, BERHAMPUR, ORISSA – 761008, INDIA
V 1) (a) R FC FC F = µR W (b) FALSE. The theorem of transmissibility of a force is limited to those problems of statics in which we are interested only in the conditions of equilibrium of a rigid body and not with the internal forces to which it is subjected. (c) The center of gravity is a geometric property of any object. The center of gravity is the average location of the weight of an object. The point is dependent on both density distribution and 3 dimensional geometry of the object. Center of volume depends on only 3 dimensional geometry of the object. (d) If the mass centre of a body or a particle of mass m is subjected to a net force F and it acquires an acceleration a, then Or 0 This is indeed a restatement of Newton’s law but it suggests that the term may be considered as a fictitious force, often called D’Alembert’s force or the inertia force. We take this equation as equation of equilibrium; thereby reducing the dynamic problem to that of a statically problem. (e) The method of section is preferred over method of joint under the following situation:‐ • In the analysis of large truss in which forces in only few members are required. • If method of joint fails to start or proceed with analysis for not getting a joint with only two unknown forces. (f) u = 200 m/s θ = 45o (maximum range case) as we know (g) v = u + at v u t . 28.83
(h) Coefficient of restitution = Or e The statement is: relative velocity of particle after impact is coefficient of restitution time’s relative velocity before impact. 0; For the case of perfectly plastic impact 1; For the case of perfectly elastic impact 0 1; For the case of perfectly semi‐elastic impact (i) , (j) The basic involved in the “Principle of virtual work” is the virtual displacement. For the solution of problems of mechanics, whether a body is actually at rest or in motion a virtual or possible displacement can be visualized in view of the constraints. Such a displacement is hypothetical or imaginary; it may or may not be along the actual displacement but it must be one of the physically possible displacements only. The term virtual work therefore implies the hypothetically work which would have been done to result in a virtual displacement under the application of the given system of forces and couple moments. So, it is clear that, the word virtual is instead of infinitesimal, hypothetical imaginary.