The big idea driving this unit
A car speeds down a road, crashes head-on into a pole, and crumples on impact — while a crash-test dummy strapped to the open truck bed behind it keeps sliding forward and flies off. Every topic in this unit helps explain a different piece of why that happens.
Chapters in this unit
- 1 Frames of ReferenceIf you watched the crash from inside the car, from the sidewalk, and from a helicopter overhead, would the car look like it was moving the same way each time?
- 2 Speed and Distance/Time GraphsCould you have predicted exactly how the crash would unfold just by looking at a graph of the car's motion before impact?
- 3 Inertia and Net ForcesWhat actually causes the crash-test dummy to go flying off the truck bed the instant the truck hits the pole?
- 4 Energy Transfer via FrictionAfter the crash, the truck screeches to a stop instead of sliding forever — where does all that motion energy actually go?
- 5 Mass and AccelerationIf you wanted to make a crash less damaging, would it matter more to slow the truck down or to make it lighter?
- 6 Collisions and Newton's Third LawThe pole doesn't move and looks fine, but the truck crumples badly — does that mean the pole pushed on the truck harder than the truck pushed on the pole?