HiSET Science: Weight and Mass

Weight
Too often, weight is confused with mass. Strictly speaking, weight is the force pulling a body towards the center of a nearby astronomical body. Of course, in the case of most day-to-day operations for human beings, that astronomical body is the earth. The reason for weight is primarily a gravitational attraction between the masses of the two bodies. The SI unit for weight is the Newton. In general, we will be concerned with situations in which bodies with mass are located where the free-fall acceleration is g. In these situations, we may say that the magnitude of the weight vector is W = mg. As a vector, weight can be expressed as either -mgj or -Wj, in which j is the direction on the axis pointing away from the earth.