Lesson 5 of 12 · Momentum
Experiment⭐ 30 XPRecoil and Explosions
Recoil and Explosions.
🎯 Your mission
Predict it first. Then prove yourself right (or wrong).
⚡ The twist
Nature loves to surprise the careful watcher.
Mind = Blown
🔬 The more you look, the more nature shows you.
Make a hypothesis first
Before you start: write down what you think will happen, and why.
What You'll Learn
When a stationary object separates into parts, total momentum stays zero, so the parts must carry equal and opposite momenta. A light part therefore leaves faster than a heavy one — a rifle recoils slowly while the bullet leaves quickly.
Key Words
Tap a word to see its definition.
Materials Needed
- two trolleys of different mass
- compressed spring
- track
- metre rule
Safety First
- Release the spring away from faces and end-stop the track.
Steps
Read the explanation above and note the two key terms before you start.
Compress a spring between two trolleys of different mass, release them, and measure how far each travels before friction stops it. Show the mass-velocity products are equal and opposite.
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 2A rifle recoils more slowly than the bullet leaves because the rifle:
Where you see this in real life
This shows up in your everyday life more than you'd think.
Stretch Challenge
Try this in real life this week.
Try one experiment in real life this week — even a tiny one.
For the dinner table
“What's the most surprising thing you learned today?”
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?
Recoil and Explosions
Predict it first. Then prove yourself right (or wrong).
Full screen — no distractions
Checkout complete lesson on Momentum for 9th Grade
Get the full Momentum track as a printable PDF — all lessons, worksheets, and answer keys.