Basics of Mechanics Mechanical Engineering Notes | EduRev

Basics of Engineering Mechanics

From the very childhood we have seen footballs bouncing and wheels rolling. We might have wondered how all these motions happen. These all motions are interaction of different bodies and effect of forces acting on them. The branch of science dealing with the effect of forces on bodies is called Mechanics

The principles of Mechanics are exactly applicable to machines, it may be a simple machine such as a liver or bicycle or a machine as complex as an aircraft. When Mechanics is applied in Engineering, design and analysis of mechanisms and machine, it is called as Engineering Mechanics.

When bodies interact and forces act between them there are two possibilities, they may move or they may remain static. The branch of Engineering Mechanics dealing with the motion of bodies is called as Dynamics and the other branch is called as Statics, in which we study balance and equilibrium of bodies.

Throughout the study of Engineering Mechanics the principles of three Newton's Laws of Motion are used invariably. So complete understanding of these laws is a must. Along with this, as the physical quantities encountered during engineering analyses are mostly vectors, the adequate knowledge of vector algebra is required.

Statics

This branch of engineering mechanics deals with bodies in equilibrium and are not moving with respect to the frame of reference considered for analysis. Bodies may be experiencing different forces but the configuration of these forces is such that the resultant force on the system is zero.  The unbalanced forces tend to accelerate a body but if net force is zero the body will not accelerate. In addition to accelerating a body forces make bodies rotate. This ability of a force to rotate a body is called as torque or moment of the force. For true static equilibrium the net moment or torque on a body should also be zero along with zero net force.

Statics include force analysis in stationary structures such as trusses, frames and machines at certain stationary positions. Cables and strings in stationary positions in mechanical systems also comes under the purview of statics.

Dynamics

The analysis of forces and motion in moving bodies comes in Dynamics. This branch of engineering mechanics is further divided in two branches, kinematics and kinetics. Kinematics deals with the analysis of motion of bodies without considering the forces causing or associated with these motions. In Kinematics the position, velocity and acceleration of certain points and the members of mechanisms and machines is studied. The kinematic analysis starts with particles and is then extended to rigid bodies. The forces causing motion in bodies are studied under kinetics. Kinetics include analysis of causal force, impulse and momentum of bodies. The concept of work and energy, and its application for analysis of mechanical systems also comes in this branch of dynamics.