1.2.A.1–2Concept
Using the object model, an object's size, shape, and internal configuration are ignored, and it may be treated as a single point with extensive properties such as mass and charge. Displacement is the change in an object's position: Δx = x − x₀.
ExampleWhy a truck can be a point1 / 3
A delivery truck is 8 m long, with a complicated internal layout of cargo and an engine. (a) Explain what the object model allows you to ignore about the truck when analyzing its motion down a highway. (b) Explain what the model does NOT discard — what still rides along with that single point.
Try it on paper first, then reveal each step to check your work.
Step 1 — What gets ignored
The object model lets you ignore the truck's size, shape, and internal configuration (how the cargo and engine are arranged inside it) — none of that is needed to predict where the truck as a whole goes.