Navigation
Analyzing what happens when objects collide and how we use physics to stay safe.
Why does a car's front end crush like a soda can during a crash, and why is that actually the very thing that saves your life?
Quick Check
If a bug hits a bus windshield, which object experiences the greater force of impact?
Answer
They both experience the exact same amount of force.
Imagine a passenger stopping during a crash. 1. Without an airbag, the passenger hits the dashboard and stops in seconds. 2. With an airbag, the passenger sinks into the cushion, stopping in seconds. 3. Since the time increased by times, the force felt by the passenger is reduced to th of the original impact. This is the difference between a minor bruise and a major injury.
Quick Check
Why do athletes bend their knees when they land after a high jump?
Answer
To increase the time of the impact, which reduces the force felt by their joints.
Modern cars are designed with crumple zones—areas at the front and back specifically built to collapse easily. This might seem like bad engineering, but it is intentional. When a car 'crumples,' it is doing two things: it is absorbing energy and increasing the duration of the collision. Instead of the car stopping dead in its tracks (high force), the crumpling acts like a mechanical spring that slows the stop down. This ensures the 'survival cell' (where the people sit) experiences a much gentler deceleration.
If Object A hits Object B with a force of N, how much force does Object B exert on Object A?
Which of these is the primary goal of a car's crumple zone?
A person landing on a soft mat experiences less force than landing on concrete because the mat increases the time of the stop.
Review Tomorrow
Tomorrow, try to explain to a friend why catching an egg with 'soft hands' (moving your hands backward) prevents it from breaking.
Practice Activity
Find three items in your house designed to reduce impact force (Hint: Look in your kitchen or sports gear) and identify how they increase 'impact time'.