Stopping Distance

When you're in a moving car, stopping isn't instant—it happens in two stages. Thinking distance is how far the car travels while the driver reacts and hits the brakes. This distance increases if you're tired, distracted, or under the influence of drugs or alcohol.

The braking distance is how far the car travels after the brakes are applied. Poor brakes, wet roads, or a heavier vehicle all increase braking distance. Both thinking and braking distances increase with speed—the faster you go, the longer it takes to stop!

When brakes are applied, friction between the brakes and wheels converts kinetic energy into heat energy, warming up the brakes and slowing the vehicle. Your total stopping distance is simply thinking distance + braking distance.

Practical tip: Remember that stopping distances increase dramatically with speed! Doubling your speed doesn't just double your stopping distance—it makes it much longer.

Terminal Velocity

Objects falling through air experience two main forces: weight pulling them downward (caused by gravity) and air resistance pushing against their motion. These forces create three distinct stages of falling.

Initially, the object accelerates downward because its weight exceeds air resistance. As speed increases, air resistance grows stronger while weight remains constant. Eventually, these forces balance perfectly, and the object reaches terminal velocity—a constant speed where it no longer accelerates.

This is why skydivers reach a steady falling speed and why raindrops don't hit the ground at lethal speeds. Without air resistance (like in space), objects would continue accelerating indefinitely!

Fun fact: A skydiver falling spread-eagle reaches terminal velocity at about 120 mph, but by tucking into a dive position, they can reach speeds over 200 mph!