First Newtons law If an object experiences no net force, then its velocity is constant: the object is either at rest (if its velocity is zero), or it moves in a straight line with constant speed (if its velocity is nonzero). Second Newtons law The acceleration a of a body is parallel and directly proportional to the net force F acting on the body, is in the direction of the net force, and is inversely proportional to the mass m of the body: F=ma, [N] we can also describe it as F=ma=m dv dt F= dp dt , where: m - mass of the object a - acceleration v - velocity of the object t - time Third Newtons law When a first body exerts a force A on a second body, the second body simultaneously exerts a force B = −A on the first body. This means that A and B are equal in magnitude and opposite in direction. Weight force Weight of an object is defined as the force of gravity on the object. On the Earth, gravity force is defined as: Fg=mg, where: m - mass g - acceleration due to gravity Normal force The normal force is the support force exerted upon an object that is in contact with another stable object. For example, if a rock is resting upon a ground, then the surface is exerting an upward force upon the rock in order to support the weight of the rock. Static friction Static friction it is friction between two or more solid objects that are not moving relative to each other. TS=μSN, where: N - normal force μS - coefficient of static friction Kinetic friction Kinetic friction occurs when two objects are moving relative to each other. TK=μKN, where: N - normal force μK - coefficient of kinetic friction
Posted on: Mon, 24 Nov 2014 04:04:29 +0000