Physics
Free-Body Diagrams and Newton's Laws
About this book
Predict it. Diagram it. Explain it.
Why does a cart speed up, slow down or keep rolling? Learners describe motion from a reference point, read position–time graphs, draw labeled force diagrams and use net force and mass to predict acceleration. Every lesson follows the same seven LessonCrest steps, from a readiness check to explained answers.
- Distance, displacement and average speed
- Position–time graphs with real units and gridlines
- Force diagrams, balanced and unbalanced forces
- Net force, mass and acceleration (a = Fnet ÷ m)
With explained answers for every page
Look inside
What this book covers
Covered
This book helps you describe motion from a reference point, read position–time graphs, draw force diagrams, and use net force and mass to predict how motion changes.
Not covered
- Everything moves along one straight line, and every force points left–right or up–down.
- Angled forces, momentum, energy and speed–time graph calculations come later, in the Physics: Free-Body Diagrams and Newton's Laws book.
Before you start, you should be able to
- Measure distance in meters and time in seconds
- Find a unit rate, such as meters per second
- Read a value from a graph's axes
- Tell an observation from a prediction
Things to have
Any activity in this book uses toy cars or carts on a clear floor; adults should check the space first.
Notices
This book teaches introductory physical science. Activities use only toy cars or carts rolled on a clear floor with adult approval.
Pictures in this book are simplified learning models. Check answers with the explanations at the back of the book.
The steps in this book
- Step 1: Get Ready
Check the skills you need before you begin. If something feels tricky, an adult can help you start in the right place.
- Step 2: Learn It
Read a short, clear explanation of the new idea and the words that go with it.
- Step 3: See It
Watch the idea being used, one step at a time, in a worked example.
- Step 4: Try It Together
Practice with prompts and help cues. The help gets smaller as you get stronger.
- Step 5: On Your Own
Practice on your own with different kinds of questions, and explain your thinking.
- Step 6: Look Back
Look back at earlier learning so it stays strong, then check where to go next.
- Step 7: Check and Fix
Check your answers. Each answer explains why, names a common mistake, and shows how to fix it.
What is in the book
The modules
- Module 1: Describe motion with a referencePages 5–14
- Module 2: Read motion in graphsPages 15–24
- Module 3: Forces combine into a net effectPages 25–34
- Module 4: Connect evidence to predictionsPages 35–44
Contents
- Readiness check, pp. 3–4. Before Module 1. Its table tells you where to start.
- Modules, pp. 5–44
- Checkpoints, pp. 14, 24, 34, 44. The last page of each module.
- Mixed review, pp. 45–48. Questions from across the book, mixed together.
- Exit check, pp. 49–50. A last check across the book.
- Reflect and repair, p. 51
- Try again, p. 52. Fresh questions like those in the exit check.
- Extra practice, p. 53
- Answers and explanations, pp. 54–64. Notes in this part are headed “Why”, “Common mistake”, “Help” and “Look for”.