When we say that a person or object "weighs" a certain number of pounds, we refer to a measure of force. (response 'b.')

Forces are measure in units of pounds (English) or Newtons (metric). An object's weight is a measure of the force with which gravity acts on it. An object demonstrates different weights on the earth and moon, because gravitational forces differ in those two environments. However, that object's mass is constant. Mass, measured in units of slugs (English) or kilograms (metric) informs us about how much matter an object contains and, hence, how much resistance it offers to any force that it encounters.

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