motion of a particle is caused by exposure to certain forces or forces that give it acceleration.The result of the application of force certain value for a certain time a corresponding amount of movement.Impulse force is a measure of its validity over time: Pc = favg • Δt, gdeFsr - the average force acting on the body; Δt - time interval.
Momentum is momentum body.It is a vector quantity, codirectional rate and equal to the product of its body weight: Pt = = m • v.
Thus, momentum force is changing momentum and body: Pc = ΔPt = m • (v - v0), gdev0 - the initial velocity; v - the ultimate speed of the body.
This equation shows Newton's second law with respect to an inertial reference frame: the derivative of a material point in time is e
qual to the value of the constant force acting on it: favg • Δt = ΔPt → favg = dPt / dt.
total momentum of several bodies may change only under the influence of external forces, and its value is directly proportional to their amount.This is a consequence of the second and third laws of Newton.Suppose that the system consists of three interacting bodies, then right: Ps1 + Pc2 + Pc3 = ΔPt1 + + ΔPt3 ΔPt2, gdePci - momentum force , acting on the body i; Pti - momentum body i.
This equation shows that if the sum of the external forces is zero, then the total momentum closed system of bodies is always constant, despite the fact that the internal force change their momentum s.This principle is called the law of conservation of momentum well.It should be borne in mind that it is a vector sum.
In reality, the system of bodies are rarely closed, since it always operates at least the force of gravity.It changes the momentum of vertical, but does not affect him, if the motion is horizontal.