🧭 Plot Summary
Last time you learned to count an object’s momentum. Now the real question: how do you change it? Stopping a moving object means taking its momentum from something to zero, and that takes a force acting for some amount of time. Together, force and time make impulse.
Here is the surprising part. For a given stop, the change in momentum is fixed. But you get to choose how it’s shared between force and time. Stretch the time out and the force shrinks. That single idea explains airbags, crumple zones, padded bumpers, and why a well-packed egg survives a fall that would break a bare one.
What you will do in this activity
- Learn the impulse-momentum theorem: force times time equals the change in momentum.
- Drop a ball into different materials and use the crater depth to estimate how long the stop took and how big the force was.
- Compare a ball that bounces with one that sticks, and see why a bounce takes a bigger impulse.
- Explore force-time graphs and see why a longer stop means a smaller force for the same impulse.
- Work out how much cushioning an egg needs to survive a drop, a preview of Project 5-1-4.
Why it matters
Almost every safety device you’ve ever used works by lengthening the time of a stop. This is the physics behind your egg-drop container in Project 5-1-4 and the crumple zones you’ll evaluate in Problem 5-3-1.
✅ Self-Check Before You Roll On
Check off each item as you get there. These are not grades — they are your own signal.