Final answer:
The discrepancy in Newtons measured arises from the friction encountered when pulling objects across a surface, unlike when weighing them where only gravitational force is measured. Mass represents the amount of matter and remains constant, while weight can vary due to changes in local gravity.
Step-by-step explanation:
The difference in the number of Newtons measured when weighing objects versus when pulling them across a surface can be attributed to the presence of friction. When weighing an object, what is being measured is the force of gravity acting on the object's mass, which can be calculated using the formula weight = mass * gravity (W = m*g). This weight represents the object's gravitational force and does not change unless the object's mass or the strength of the gravitational field changes.
However, when pulling the object across a surface, the force required not only has to overcome the gravitational pull but also the force of friction between the object and the surface. Specifically, the actual force applied (F = m*a) must be sufficient to cause acceleration, and this acceleration can be reduced due to friction. Consequently, the measurements differ because the force required to move the object across a surface includes additional resistance that must be overcome, which is not present when simply weighing the object.
Mass and weight, while related, are distinct; mass is an intrinsic property that does not change with location, while weight depends on the local gravitational force. Friction is a key factor that affects measurements when pulling objects, and it is influenced by the texture and nature of both the surface and the object in contact with it.