 Hello everyone, myself, Ms. Shailaja Devarkonda Assistant Professor in Civil Engineering Department Walsh and Institute of Technology, Sulapur. In today's lecture, we are going to study Introduction to Engineering Mechanics. At the end of this session, the students will be able to know the classification of engineering mechanics and the basic terminologies used in the engineering mechanics. The mechanics is classified in two types, one is solid mechanics of solid and mechanics of fluid. Again, this mechanics of solid is further classified into mechanics of rigid bodies and the mechanics of deformed bodies. The mechanics of rigid bodies is further classified in statics and dynamics. Dynamics means it is the study of the body or any particle at the rest. Dynamics means again it is classified further kinetics and kinematics, so it is the study of the body in motion. Now, this mechanics of deformed bodies is further classified as theory of elasticity and theory of plasticity. The mechanics of fluids is classified as ideal fluids, viscous fluid, incompressible fluids. So, in this work, we are studying the properties of water, all other liquids and engineering mechanics. We are going to study the mechanics of rigid bodies, statics and dynamics both. Now, these are the basic terms used in the engineering mechanics, mass. What is the quantity of matter possessed by a body? The SI unit of mass is kg, time is the major of succession of events. Again, the SI units of time is seconds, not space, the geometric region in which the study of body is involved. The next term is length, is the concept of measuring linear distances and the SI unit of length is meters. Linear distances means the distance in a straight line means the next term is displacement. The distance travelled by the body or a particle in a specified direction, velocity. The rate of change of displacement with respect to time is known as velocity and the SI unit of velocity is meter per second, acceleration. The rate of change of velocity with respect to time, normal SI unit of acceleration is meter per second square. The next term is momentum. The product of mass and velocity is called as momentum and the SI unit of momentum is kg meter per second. The next term is rigid body. The body in which the position of the particles will not change. After the application of any external force, it is called as rigid body particle. Any object which has only mass is known as particle means the particle will not have any specific shape or any specific size. So these are the basic terminologies used in the engineering mechanics. These are the some laws used in the mechanics on which further study depends. The basic laws we are using are Newton's first law, second law, third law, Newton's law of gravitation, law of transmissibility of forces and law of parallelogram. First law, it state that the everybody continues in its state of rest or in its uniform motion in a straight line unless until it is acted by any external agency. Since a body will continue its position or its motion, means uniform motion, until unless you will apply the external force. Then Newton's second law, it state that the rate of change of momentum of a body is directly proportional to the impressed force and it takes place in the direction of the force acting along it. That is F is directly proportional to the rate of change of momentum. What is the momentum? It is nothing but the mass into velocity. Again if you consider mass will not change, mass of any body will not change unless until the external force is acting on this. Mass of any body will not change unless until it is acted by the external agency. Only the velocity will change. So it is nothing but the F is directly proportional to mass into rate of change of velocity. What is mean by rate of change of velocity? It is nothing but the acceleration. So from this you will directly get F is directly proportional to M into A. Then Newton's third law, at every action there is equal and opposite reaction. For then Newton's law of gravitation. The force of attraction between any two bodies is directly proportional to their masses and inversely proportional to the square distance between them. So from this you will get that is F is equal to G into M1 M2 upon D square. The next law is law of transmissibility of forces. It states that any force is acting on the body. It is replaced by another force of the same magnitude and same line of action but anywhere on the surface of the body, law of parallelogram. If two forces are acting simultaneously on the sides of parallelogram in representing its magnitude and direction, then the resultant of these forces is represented by the diagonal of the parallelogram in magnitude and direction. So these are the basic laws we are using in the further study. Now scalar and vector quantities. Scalar and vector quantities. Vector quantities are those which are having only magnitude, no direction and the vector quantities are having magnitude and the direction itself. So examples for scalar quantities as length, mass and time for vector quantity, force, velocity and acceleration. In engineering mechanics, we will study about the force means what is force, how force is acting, what are the effects of the force on the rigid bodies. So the force is the external agency which tries to change the state of rest or uniform motion of the body. Means if you considering any rigid body at state of rest or any uniform motion unless until you will apply any external force on that body, it will remain same in its position. Once you are applying any external force on that body, it will change its state of rest or it will change its uniform motion. So this agency is called as the force, the SI unit of force is Newton. This force is further expressed in four terms which are called as characteristics of force. Those are magnitude, point of application, line of action and direction. How to explain the force by these four points? So in figure one, I have shown one ladder which is resting on the supporting walls at point A and B. So here I can explain that this force of 100 kilo Newton means 100 kilo Newton is the magnitude of the force. This force of 100 kilo Newton is acting 2 meter from the point A which is nothing but the point of application means it is acting at the point C. But how you define? So it is acting at the 2 meter from the point A which is nothing but the point of application and line of action. This force is acting vertical, this figure this 100 kilo Newton force is acting vertical and the direction fourth one is direction it is acting downward. So the force is defined as magnitude, point of application, line of action and direction. So likewise we have to express the force. Then movement, any rotational effect caused by the force on body is known as movement of a force or a movement. In this figure you can see it is a hinged type beam, hinged means one end is fixed and another end is free. This force F is acting at the end of this beam. It is acting downward means here is no support at this point so this will rotating like this. So which is nothing but the clockwise direction. This force is rotating in clockwise direction about the axis of rotation, axis of rotation which is nothing but the fixed point is called as the movement that is force into distance is nothing but the movement. For example you can consider the doors, doors are fixed at the one end and free at other end. So hinges are provided to the door and wall so you can easily rotate flip it up. You can open and you can close the doors. So it is best example of the movement and the rotation of force is in clockwise direction it is considered as the positive movement where it is in anti-clockwise direction it is called it is considered as negative direction. If you in this figure this force F is acting downward so means it is rotating about this fixed point in clockwise direction clockwise it will cause the positive movement. Now you pause this video and try to answer this questions. So these are the answers, these are the references considered for the study. Thank you.