Category: Mechanical Engineering

Pantograph: It is a mechanism which is used trace a path to an enlarged or reduced scale. It is an example of four bar kinematic chain. It consists of a four links joined in such a way to form a parallelogram ABCD in which AB=CD and AD=BC. In figure, OAE always remains in straight line. […]

Ohm’s law: The current flowing through a conductor is directly proportional to the potential difference across the ends of the conductor and inversely proportional to its resistance. If V is the potential difference across the ends of a conductor, R is its resistance and I is the current passing through it then as per the […]

Octane number: Octane number is defined as the percentage by volume of iso-octane (2, 2, 4-trimethyl pentane) in a mixture on n-heptane and iso-octane. Octane number is a measure resistance of gasoline (petrol) to knocking in spark ignition internal combustion engines. Example-If a gasoline contains 80% of iso-octane and 20% of n-heptane then the octane […]

Moulding sand: Moulding sand (Foundry sand) is used to make mould in sand casting process. Molding sand is found on the bottom and banks of rivers and lakes. It is formed by breakdown of rocks due to natural forces like wind, rain, water currents and heat. Main constituents of Moulding sand: Silica sand – It is […]

Mechanical properties of materials: Elasticity:The tendency of a material to regain its original dimensions (size and shape) upon the removal of load or force. Eg. Steel is more elastic than rubber. The ratio between tensile stress and tensile strain or Compressive stress and compressive strain is called young’s modulus of Elasticity. Young’s Modulus of elasticity […]

Machine: It is a combination of mechanisms which receives energy and uses it for doing some useful work. The machine does not work by itself. It does work only when energy is supplied to it. Some of the basic machines are (i) lever  (ii) screw  (iii) wedge  (iv) pulley  (v) wheel and axle  

Laser Beam Machining (LBM): LASER stands for “Light Amplification using Stimulated Emission of Radiation”. This process utilizes the energy of coherent photons. Light energy (by flash lamp or energy source) of a particular frequency is thrown on to the laser tube (Ruby rod) to excite the atoms of the inside media. The electrons from laser […]

Kirchoff’s law: Kirchoff’s First law or Current Law: In current carrying coils, the algebraic sum of all currents meeting at a junction is zero. The incoming currents are considered as positive and the outgoing currents are considered as negative. According to Kirchoff’s law I1 + I2 – I3 + I4 + I5 – I6 + I7 = 0 Kirchoff’s Second Law or Voltage […]

Kinematic pair: Kinematic Pair: When the two Kinematic links are joined to have relative motion between them is known as Kinematic pair. The Kinematic pairs are classified as follows. Acc. to the nature of contact Lower pair – When the two links have surface contact between them, it is known as lower pair. Higher pair – When the […]

Kinematic chain: When a number of kinematic links are joined in such a way that the last link is joined to the first link and the relative between them is a definite. If the motion is not definite then it is called non-kinematic chain. There are two equations to find out whether the Chain is […]