1 A Presentation on Department of Mechanical Engineering, SSPM’s College of Engineering, Harkul, Kankavli, 416602 2021-2022 Resolution of Forces By Prof. A S Pendse
Content 2 What is Engineering Mechanics? Classification of Mechanics Syllabus Force Newton’s Laws of Motion System of Forces Resolution of Forces Numericals
What is Engineering Mechanics It is the branch of physics which deals with the study of forces and the effect of forces on the bodies ,which are at rest or in motion . Mechanics term was first introduced by Sir Isaac Newton in the 15 th century Engineering Mechanics subject is totally based on Newtonian Mechanics
Classification of Mechanics
Branch of engineering Mechanics which deals with effect of forces on the bodies which are at rest( not moving) e.g . Forces calculation in cable supporting electricity pole, Calculation of forces in truss member, calculation of friction etc. Branch of Engineering Mechanics which deals with effect of forces on bodies which are in motion e.g . Projectile motion analysis, equation of motions, NSL for moving objects Classification of Mechanics
Force: A force is any interaction that, when unopposed, will change the motion of an object. A force can change state of rest or state of motion A force can cause an object to change its velocity i.e. to accelerate or decelerate. Bodies: A body is another word someone can use to describe an object with mass. We can refer body to very small objects like a ball, book a small stone and also we can refer to very large objects like heavy machines, cars, airplane, Building etc . Force
ENGINEERING MECHANICS FORCE:
Newton’s Laws of Motion 1 st Law:- An object at rest remains at rest, and an object in motion remains in motion at constant speed and in a straight line unless acted on by an unbalanced force
Newton’s Laws of Motion 2 nd Law:- The rate of change of momentum of a body is directly proportional to applied force and takes place in the direction of net force. F (P-momentum) P = mv Change of momentum = final — initial = (mv 2 ) — (mv 1 )
Newton’s Laws of Motion 3 rd Law:- For every action (force) in nature there is an equal and opposite reaction
System of Forces System of forces is a collection of forces and couples acting on an object System of forces is a term used to describe the group of forces. M F=W Friction F=N F=2N F 1 =10N F=W
Classification of Force Syatems
Coplanar Forces: If all the forces are acting in single plane
F1 F3 F2 F4 F5
A board supported by 4 cables
Non Coplanar forces: If the forces are acting in different planes F1=10N F1=5N F1=20N
Concurrent forces : If the line of action of all forces passes through single point, such force system is called as concurrent force system
Parallel Forces: W=500N W=700N W=600N W=400N
General Force System: Forces are acting at different points and in different direction c c c c c F1 F3 F5 F4 F2
Resolution of force implies breaking a single force into two components(parts), such that if components combined together would have the same effect . Resolution of Forces
Principle of Transmissibility: A force being a sliding vector continues to act along its line of action and therefore makes no change, if it acts from different point on its line of action on a rigid body.