Engineering Mechanics PDF

ENGINEERING MECHANICS \- may be defined as the science which considers the effects of forces on rigid bodies. The subject divides naturally into two parts: statics and dynamics. › STATICS \- we consider the effects and distribution of forces on rigid bodies which are and remain at rest. MOMENT...

ENGINEERING MECHANICS \- may be defined as the science which considers the effects of forces on rigid bodies. The subject divides naturally into two parts: statics and dynamics. › STATICS \- we consider the effects and distribution of forces on rigid bodies which are and remain at rest. MOMENT OF FORCE \- measure of its ability to produce turning or twisting about the axis \- magnitude of moment force about an axis which is perpendicular to a plane containing the line of action of the force is defined as the product of the force and the perpendicular distance from the axis of the line of action of the force COUPLES \- magnitude of the resultant (0) RIGID BODY \- rigid body is defined as a definite amount of matter the parts of which are fixed in position relative to each other FORCE \- may be defined as that which changes, or tends to change, the state of motion of a body. \- This definition applies to the external effect of a force. \- The INTERNAL FORCE of a force is to produce stress and deformations in the body in which the force acts. CHARACTERISTICS OF FORCE \- (1) It's magnitude \- (2) The position of its line of action, and \- (3) The direction in which the force acts along its line of action PRINCIPLE OF TRANSMISSIBILITY \- of a force states that the external effect of a force on a body is the same for all points of application along its line of action FORCE SYSTEM \- is any arrangement where two or more forces act on a body or on group of related bodies. COPLANAR \- When the lines of action of all the forces in a force system lie in one plane. CONCURRENT FORCES \- Forces whose lines of action pass through a common point. PARALLEL FORCES \- whose in which the lines of action are parallel. \- The resultant of such system is determined when it is known in magnitude, direction and position. NON-CONCURRENT FORCES \- those in which the lines of action neither are parallel nor intersect in a common point. FREE BODY DIAGRAM \- A sketch of the isolated body which shows only the forces acting upon the body. APPLIED FORCES \- The forces acting on the free body are the action forces. SCALAR \- Quantities which possess magnitude only and can be added arithmetically. VECTOR \- are quantities that possess magnitude and direction. RESULTANTS OF FORCE SYSTEMS \- The effect of a systems of forces on a body is usually expressed in terms of a resultant. The value of this resultant determines the motion of the body. RESULTANT OF PARALLEL FORCE SYSTEM \- is the algebraic sum of the forces composing the system. \- The position of the resultant is determined from the condition that the moment of the resultant is equal to the moment sum of its parts. EQUILIBRIUM OF CONCURRENT FORCE SYSTEM \- resultant is (0) FRICTION \- force that resists the movement of two contacting surfaces that slide relative to one another \- It always acts tangent to the surface at the points of contact and is directed so as to oppose the possible or existing motion between the surfaces.   DRY FRICTION \- force that opposes the relative lateral motion of two solid surfaces in contact. \- static or dynamic NORMAL FORCE \- force, and its direction is perpendicular to the surfaces. COEFFICIENT OF FRICTION \- is a dimensionless scalar value which equals the ratio of the force of friction between two bodies and the force pressing them together. BELT FRICTION \- The transmission of power by means of belt or rope drives or the braking of large loads by means of band brakes depends upon the frictional resistance developed between the belt and the driving or resisting surface with which it is contact. ANALYSIS OF STRUCTURE \- is the process by which we determine how the loads applied to a structure are distributed throughout the structure. METHOD OF JOINTS \- The assumption that all the members of a truss are two-force members carrying axial loads means that the free-body diagram of any of joint is a concurrent force system in equilibrium. \- METHOD OF SECTIONS \- permits us to determine directly the force in almost every member instead of proceeding to that member by a joint-to-joint analysis.