Arm and leg weakness can be caused by a variety of different conditions, some of them temporary and others chronic. Excessive exercise is one cause of temporary fatigue in the major muscle groups, although this is not considered true muscle weakness.
Mass is an intrinsic property of the body and gravity is the force exerted on any body by the things that surround it. Weight, on the other hâ¦and, depends on gravity. It is equal to the product of the mass of the body and the gravitational force acting on it.
1 Weight: force due to gravity -9.81m/sÂ². 2  Force: a pushing or pulling action that causes a change of state (rest/motion) of a body is proportional to mass x acceleration. 3  It is measured in Newtons (N) where 1N is the force that will produce an acceleration of 1 m/sÂ² in a body of 1kg mass.