The use of the pound force constrains the mass unit to an inconveniently large measuring unit called a 'slug'. However, in the US common units, the pound is the unit of force (and therefore weight).The pound is the widely used unit for commerce. The associated SI unit of force and weight is the Newton, with 1 kilogram weighing 9.8 Newtons under standard conditions on the Earth's surface. The kilogram is the SI unit of mass and it is the almost universally used standard mass unit. Then click outside the box to update the other quantities.Īt the Earth's surface, where g=9.8 m/s 2 : You can view the weight as a measure of the mass in kg times the intensity of the gravity field, 9.8 Newtons/kg under standard conditions.ĭata can be entered into any of the boxes below. Another approach is to consider 'g' to be the measure of the intensity of the gravity field in Newtons/kg at your location. The value of g allows you to determine the net gravity force if it were in freefall, and that net gravity force is the weight. You might well ask, as many do, 'Why do you multiply the mass times the freefall acceleration of gravity when the mass is sitting at rest on the table?'. Since the weight is a force, its SI unit is the newton.įor an object in free fall, so that gravity is the only force acting on it, then the expression for weight follows from Newton's second law. The weight of an object is defined as the force of gravity on the object and may be calculated as the mass times the acceleration of gravity, w = mg. Since the weight is a force, its SI unit is the newton. The weight of an object is the force of gravity on the object and may be defined as the mass times the acceleration of gravity, w = mg. While the mass is normally considered to be an unchanging property of an object, at speeds approaching the speed of light one must consider the increase in the relativistic mass. The usual symbol for mass is m and its SI unit is the kilogram. All mechanical quantities can be defined in terms of mass, length, and time. Definitions of mass often seem circular because it is such a fundamental quantity that it is hard to define in terms of something else.

The mass of an object is a fundamental property of the object a numerical measure of its inertia a fundamental measure of the amount of matter in the object.

Volume calculator with density and mass