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Chapter 4: Motion and Forces

Difficulty Level: At Grade Created by: CK-12


It’s a bird! It’s plane! It’s a super skateboarder! This boy appears to be flying high in the sky, but he can’t stay airborne for long. Gravity will soon pull him back to the ground. How was he able to overcome the force of gravity and rise into the air? In this unit, you’ll learn about forces such as gravity and motions such as skateboarding, including how skateboarders can seem to defy gravity. Along the way, you can also pick up some cool skateboarding tips!

Chapter Outline

Chapter Summary


This unit includes the concepts of motion, speed, velocity, and acceleration. Forces are introduced, including friction, gravity, elastic force, and forces in fluids. Newton’s laws of motion are examined in detail. The unit also defines work and power, and explains how machines help us do work.

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Difficulty Level:
At Grade
7 , 8
Date Created:
Jul 19, 2013
Last Modified:
Sep 10, 2015
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