MASS/WEIGHT/MOMENTUM. • • • • • • • • • • • • • • • • • • • • • *The mass is a matter contained in a body, its expressed in kilogram (kg). * The weight of a body is a force by which it is attrected towards the centre of the earth, its expressed in Newtons (N). The relation between the mass and weight of a body is given. W = m.g * The momentum is defined as the total motion possessed by a body. Momentum = mass×velocity According to Newtons second law of motion the applied force or impressed force (P) is directly propotional to rate of change of momentum. Thus P×m (v-u/t) P×m.a or P = k.m.a k is a constant of proportionality. For the sake of convenience the unit of force adopted is such that it produces unit acceleration (1m/s2) to a body of unit mass (1kg). P = m.a = mass×acceleration In S.I system of units the unit of force is Newton (briefly written as N). A newton may be defined as the force, while acting upon a body of mass 1 kg, produces an acceleration of 1m/s2 in the direction of which it acts. 1N = 1kg×1m/s2 = 1kg-m/s2 * A force equal in magnitude but opposite in direction and collinear with the applied force or impressed force producing the acceleration is known as inertia force. F I = m.a ★ D-Alemberts Principle:- Consider a rigid body acted upon by system of forces. The system may be reduced to a single resultant force (P) acting on the body whose magnitude is given by the product of the mass of the body (m) and the linear acceleration(a) of the centre of mass of the body. According to Newtons second law of motion. P = m.a or P-m.a = 0 or P+F I = 0. Thus D-Alemberts principle states that the resultant force acting on the body together with the reversed effective force or inertia force are in equilibrium.
Posted on: Sat, 03 Jan 2015 15:02:45 +0000
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