Lesson 5 of 12 · Forces
Lesson⭐ 30 XP⚡ Spark LabFree-Body Diagrams
Free-Body Diagrams.
🎯 Your mission
Understand the idea. Then look for it everywhere.
⚡ The twist
Energy never disappears — it just hides somewhere else.
Mind = Blown
🎢 You feel weightless on a roller coaster because you and the seat are falling at the same speed.
Make a hypothesis first
Before you start: which will move faster, and why?
What You'll Learn
A free-body diagram shows one object as a dot with every force on it drawn as an arrow from that dot. Arrow length shows size and direction shows line of action. Getting the diagram right usually solves the problem before any arithmetic starts.
Key Words
Tap a word to see its definition.
Steps
Read the explanation above and note the two key terms before you start.
Draw free-body diagrams for four cases: a book on a table, a box being dragged at constant speed, a ball at the top of its flight, and a car braking. Label every arrow with its cause and mark which pairs balance.
Record what actually happened, including anything that did not match what you expected.
Write a conclusion that answers the question this lesson opened with, and state your uncertainty.
Check Your Understanding
Question 1
1 of 2On a free-body diagram you draw forces acting:
Where you see this in real life
This is why airplanes can fly and why rockets reach space.
Stretch Challenge
Try this in real life this week.
This week, find one thing in your house that turns one kind of energy into another.
For the dinner table
“Show me something at home that uses this kind of energy.”
Next Smart Experiment
We'll pick an experiment that matches exactly how you're thinking right now.
Share this experiment
Send it to a parent who's looking for a 10-minute kitchen science win.
Ready?
Free-Body Diagrams
Understand the idea. Then look for it everywhere.
Full screen — no distractions
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