Ever wonder why you go fast? Like, really fast? Think about that stomach-flip when a roller coaster drops or the blur of trees when you’re pushing a bike down a steep hill. It’s visceral. Speed isn't just a number on a speedometer; it's a complex cocktail of Newtonian physics, neurological firing patterns, and evolutionary leftovers that once kept us from being eaten by things with much sharper teeth.
Honestly, we weren't really built for 70 mph. Our ancestors maxed out at a sprint—maybe 28 mph if you were Usain Bolt—yet here we are, obsessed with pushing the needle. Whether you're an adrenaline junkie or just someone who enjoys a brisk walk, the mechanics of "fast" dictate how your body perceives the world.
The Physical Forces That Make You Move
To understand why you go fast, you have to look at the invisible hand of physics. It starts with acceleration. Constant speed is actually pretty boring to the human body. If you’re in a plane going 500 mph in a straight line with no turbulence, you can pour a cup of coffee. You don't feel the speed. You feel the change.
This is where $F = ma$ comes into play. Force equals mass times acceleration. When you hit the gas or jump off a ledge, you’re feeling the force required to change your state of motion. Your inner ear contains the vestibular system, specifically the semicircular canals and otolith organs. These tiny structures act like biological accelerometers. When you move, fluid shifts, hair cells bend, and your brain gets a frantic "Hey, we're moving!" signal.
Gravity is the cheapest way to go fast. It’s a constant pull of $9.8 m/s^2$. If you’re skiing down a mountain, you’re basically just managing a controlled fall. The friction between your skis and the snow, plus the air resistance (drag) hitting your chest, are the only things keeping you from accelerating indefinitely. Well, until you hit a tree.
Kinetic Energy and the Cost of Speed
There’s a reason speed feels dangerous. It’s because the energy involved doesn't increase linearly; it’s exponential. The formula for kinetic energy is $E_k = \frac{1}{2}mv^2$.
Notice that "squared" symbol? It’s a big deal. If you double your speed, you don't have twice the energy; you have four times the energy. This is why a car crash at 60 mph is vastly more lethal than one at 30 mph. Your body intuitively senses this. That "speed thrill" is often just your brain calculating the sheer amount of energy you’re carrying and wondering if you have the brakes to handle it.
The Dopamine Loop: Why Your Brain Craves Velocity
Why do we do it, though? Why do humans intentionally seek out high-velocity experiences like skydiving or racing?
It’s the Adrenal Medulla.
When your brain perceives high speed, it triggers the fight-or-flight response. The amygdala screams "danger," and the adrenal glands dump epinephrine (adrenaline) and norepinephrine into your bloodstream. Your heart rate spikes. Your pupils dilate to let in more light. Your lungs expand to take in more oxygen. It’s a physiological high.
But the real kicker is the dopamine. For many, the "rush" of going fast is followed by a massive release of dopamine in the nucleus accumbens—the brain's reward center. This is the same pathway involved in addiction. You go fast, you survive, your brain rewards you for being a "successful" survivor of a dangerous situation. You want to do it again.
The Flow State
There’s also a psychological phenomenon called "Flow," popularized by psychologist Mihaly Csikszentmihalyi. When you’re going fast—say, technical mountain biking or driving on a track—the margin for error shrinks to almost zero. This forces "total immersion." You can’t think about your taxes or your failing relationship when you’re cornering at the limit of traction.
You become one with the movement. Time distorts. This is often why people describe high-speed activities as "meditative." It’s the ultimate way to shut up the noise of modern life. You go fast to feel present.
Sensory Perception and the Blur
Ever notice how the ground right next to a moving car is a blur, but the mountains in the distance seem still? That's motion parallax.
Our eyes can only process so much visual information per second. As you speed up, your peripheral vision begins to lose detail. This creates a "tunnel vision" effect. Physiologically, your brain starts prioritizing what’s directly in front of you because that’s what you’re about to hit.
In the 1940s, Colonel John Stapp, known as the "Fastest Man on Earth," studied the effects of high-speed deceleration on the human body using rocket sleds. He reached speeds of 632 mph. He proved that humans can withstand much higher G-forces than previously thought, but he also suffered broken bones and burst capillaries in his eyes. He went fast in the name of science, showing us the hard limits of our "meat suit" shells.
What Slows Us Down?
You can’t talk about going fast without talking about what stops you.
- Air Resistance: This is the big one. As you go faster, you have to push more air molecules out of the way. Drag increases with the square of speed. This is why supercars need 1,000 horsepower just to go 250 mph.
- Mechanical Friction: Bearings, tires, even the joints in your knees. Everything creates heat when it moves.
- Fear: This is the internal governor. Most people have a "velocity ceiling" where the perceived risk outweighs the dopamine reward.
Actionable Steps for Safely Finding Your Limit
If you're looking to explore why you go fast in your own life—whether through sport or hobby—don't just wing it.
- Audit your equipment: Because kinetic energy increases by the square of speed, a gear failure at high speed is catastrophic. Check tire pressures, brake pads, and helmet certifications.
- Train your vision: Don't look at the "blur." Look as far ahead as possible. High-speed drivers and athletes are taught to look where they want to go, not where they are. This slows down the brain's perception of speed and gives you more time to react.
- Incremental Increases: Don't try to hit your top speed on day one. Your vestibular system needs time to calibrate to new levels of acceleration.
- Understand the surface: Friction (the coefficient of friction, specifically) is your best friend. Know how temperature and moisture affect your grip on the world.
Speed is a fundamental part of the human experience. It’s a mix of ancient survival hardware and modern technology. We go fast because we can, because it feels like flying, and because it’s one of the few things that can truly force us to live in the moment.