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Engg.Mecanics-End Examination papers

June-2010 Click on Fig to Get Large  Image.  June-2010 June-2010 Click on Fig to Get Large  Image.    December -2010 Decenber -2010

Dynamics -Key concepts 4

Direct Central Impact A collision is an isolated event in which two or more moving bodies (colliding bodies) exert forces on each other for a relatively short time. A high force applied over a short time period when two or more bodies collide is called as Impact. Types of Impact 1.Elastic Impact 2.Plastic Impact or Inelastic Impact If the two objects adhere and remain connected after the impact, the impact is said to be perfectly plastic. Coefficient of Restitution During the impact, each object can lose energy This loss in energy can be expressed as the difference in velocity after the collision divided by the difference in velocity before the collision, or The prime velocities, v B '  and v A '  are velocities after the collision. The coefficient of restitution is a measure of the energy that is lost during a collision.  For a perfectly elastic collision (e = 1), no energy is lost. The Coefficient of Restitution for small rubber balls is very c

Dynamics - Key Concepts 3

  Impulse and  Momentum     In classical mechanics, an  impulse  is defined as the integral of a force with respect to time. When a force is applied to a rigid body it changes the momentum of that body. A small force applied for a long time can produce the same momentum change as a large force applied briefly, because it is the product of the force and the time for which it is applied that is important.  The impulse is equal to the change of momentum. If both sides of the above equation are multiplied by the quantity t, a new equation results. The quantity(Force X time) is known as  impulse .  Impulse  I  produced from time  t 1  to  t 2  is defined to be where  F  is the force applied from  t 1  to  t 2 . Momentum can be defined as "mass in motion."  In terms of an equation, the momentum of an object is equal to the mass of the object times the velocity of the object. Momentum = mass x velocity    = m x v