there is a force (weight) of 16.1 kN between the car and the earth. Since 1 lb f gives a mass of 1 lb m an acceleration of 32.17405 ft/s 2 and a mass of 1 slug an acceleration of 1 ft/s 2, thenġ slug = 32.17405 lb m Example - Weight versus Mass

The proportionality constant g c makes it possible to define suitable units for force and mass. Since the EE system operates with these units of force and mass, the Newton's Second Law can be modified to In the EE system 1 lb f of force will give a mass of 1 lb m a standard acceleration of 32.17405 ft/s 2.

the unit of force is the pound (lb) alternatively pound-force (lb f).

the basic unit of mass is pound-mass (lb m).

The units for force and mass are defined independently In the English Engineering system of units the primary dimensions are are force, mass, length, time and temperature. = 32.17405 lb f The English Engineering System - EE With standard gravity - a g = 32.17405 ft/s 2 - the weight (force) of 1 slug mass can be calculated as

The weight (force) of the mass can be calculated from equation (2) in BG units as In other words, 1 lb f (pound-force) acting on 1 slug of mass will give the mass an acceleration of 1 ft/s 2. The unit of mass, the slug, is derived from the pound-force by defining it as the mass that will accelerate with 1 foot per second per second when a 1 pound-force acts upon it: In the BG system the mass unit is the slug and is defined from the Newton's Second Law (1). The three base units in the Imperial system are foot, second and pound-force. For engineers who deals with forces, instead of masses, it's convenient to use a system that has as its base units length, time, and force, instead of length, time and mass. The British Gravitational System (Imperial System) of units is used by engineers in the English-speaking world with the same relation to the foot - pound - second system as the meter - kilogram - force second system (SI) has to the meter - kilogram - second system. The Imperial British Gravitational System - BG More about the SI System - A tutorial introduction to the SI-system.a body with mass of 1 kg weights 9.807 N.a 9.807 N force acting on a body with 1 kg mass will give the body an acceleration of 9.807 m/s 2.Equation (2) for a body with 1 kg mass can be expressed as:ĩ.807 m/s 2 = standard gravity close to earth in the SI system In the SI system the mass unit is the kg and since the weight is a force - the weight unit is the Newton ( N). ≈ halfway between one-fifth and one-fourth of a pound - 0.224809 lb or 3.59694 oz.≈ the weight of one hundred grams - 101.972 gf (g F) or 0.101972 kgf (kg F or kilopond - kp (pondus is latin for weight)).The handling of mass and weight depends on the systems of units used. The weight of the same body on the moon can be calculated as

The weight of a body with mass 1 kg on the earth can be calculated as The acceleration of gravity on the moon is approximately 1/6 of the acceleration of gravity on the earth. The generic expression of Newton's Second Law (1) can be transformed to express weight as a force by replacing the acceleration - a - with the acceleration of gravity - g - asį g = gravitational force - or weight (N, lb f)Ī g = acceleration of gravity on earth (9.81 m/s 2, 32.17405 ft/s 2)Įxample - The Weight of a Body on Earth vs. Weight is the gravitational force acting on a body mass. Mass is a fundamental property of an object, a numerical measure of its inertia and a fundamental measure of the amount of matter in the object. an object with mass 1 kg on earth would have the same mass of 1 kg on the moon.Mass does not change with a body's position, movement or alteration of its shape, unless material is added or removed. Mass is a measure of the amount of material in an object, being directly related to the number and type of atoms present in the object. The fundamental relation between mass and weight is defined by Newton's Second Law. Mass and Weight are two often misused and misunderstood terms in mechanics and fluid mechanics.

Gravity g