Learn on PengiAmplify Science (California) Grade 8Chapter 1: Force and Velocity

Lesson 2: Investigating Force and Motion

Key Idea.

Section 1

Review: Definition of Force

Key Idea

Moving from observation to formal physics, a force is strictly defined as a push or a pull resulting from an interaction between two objects. A force cannot exist on its own; it requires a source and a receiver.

Whenever this interaction occurs, it dictates a change in velocity. This definition removes ambiguity: if velocity changes (acceleration, deceleration, or turning), a force is definitively acting. If velocity is constant, no net force is interacting with the object. This scientific definition provides the rulebook for solving the unit's mystery.

Section 2

Inertia and Velocity

Key Idea

Objects possess a natural tendency to resist changes to their state of motion.

A soccer ball on a field remains stationary until kicked. Similarly, a satellite gliding through deep space continues at a constant speed forever unless a thruster fires or gravity acts upon it.

Lesson overview

Expand to review the lesson summary and core properties.

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Section 1

Review: Definition of Force

Key Idea

Moving from observation to formal physics, a force is strictly defined as a push or a pull resulting from an interaction between two objects. A force cannot exist on its own; it requires a source and a receiver.

Whenever this interaction occurs, it dictates a change in velocity. This definition removes ambiguity: if velocity changes (acceleration, deceleration, or turning), a force is definitively acting. If velocity is constant, no net force is interacting with the object. This scientific definition provides the rulebook for solving the unit's mystery.

Section 2

Inertia and Velocity

Key Idea

Objects possess a natural tendency to resist changes to their state of motion.

A soccer ball on a field remains stationary until kicked. Similarly, a satellite gliding through deep space continues at a constant speed forever unless a thruster fires or gravity acts upon it.