Definition
Free fall is the motion of an object falling solely under the influence of gravity, without any air resistance or other opposing forces. In this state, regardless of weight, size, or shape, every object accelerates downward at the exact same rate.
A World Where a Feather and a Steel Ball Drop Together
Think of that stomach-dropping sensation at the top of a drop tower ride. In everyday life, a heavy bowling ball hits the ground much faster than a light feather. It seems only natural to assume that heavier objects fall faster. But there is a hidden culprit here: air.
In a room filled with air, a feather flutters down slowly because its wide surface catches the air like a sail. A steel ball, however, cuts right through it. But what happens if we pump all the air out of a giant chamber to create a vacuum? Remarkably, the feather and the steel ball hit the ground at the exact same moment.
Apollo astronauts famously tested this on the airless surface of the Moon by dropping a hammer and a feather at the same time—and they hit the lunar dirt side by side. Without air to get in the way, every object responds solely to the pull of gravity.
Why Heavier Objects Don't Fall Faster
This brings up a natural question: Gravity pulls heavier objects with much greater force, so shouldn't a steel ball accelerate faster than a feather? The key to solving this puzzle is an object's stubbornness—known as 'inertia.'
A lightweight stroller starts rolling with just a gentle push, but a heavy truck demands massive force to get moving. The more matter an object contains—that is, the greater its mass, the stronger its tendency to resist any change in motion (inertia). A heavier object is simply harder to budge.
While Earth's downward gravitational pull increases with mass, the object's resistance to moving increases by the exact same proportion. The 'stronger pull' and the 'greater resistance' perfectly cancel each other out. As a result, whether light or heavy, every object speeds up (accelerates) at the exact same rate every second.
A Closer Look at How It Works
Near the surface of the Earth, a freely falling object speeds up by about 9.8 meters per second (roughly 32 feet per second) for every second it falls. This is known as the acceleration due to gravity (often denoted as *g*). After 1 second, it falls at about 22 mph (35 km/h); after 2 seconds, it reaches 44 mph (70 km/h), steadily gaining speed.
Astronauts aboard the International Space Station aren't floating because there is no gravity. In fact, the station and everyone inside are in a continuous state of free fall toward Earth. Because the station is traveling forward so fast, the curve of its fall matches the curvature of Earth, keeping it in perpetual orbit without crashing.
When you are in pure free fall, every part of your body falls at the exact same rate. With no floor pushing back against your feet, you feel completely weightless. That brief, floating feeling when an elevator drops suddenly—or at the peak of a rollercoaster—is this very same phenomenon in action.
Common misconceptions
Heavier objects naturally fall faster than lighter ones.
In everyday life, a feather falls slowly because of air resistance. In a vacuum with no air, a heavy steel ball and a light feather fall at the exact same speed.
Astronauts float in the Space Station because there is zero gravity in space.
Gravity in the Space Station's orbit is nearly 90% as strong as on Earth's surface. Astronauts float because both the station and the crew are in a perpetual state of free fall together.
Where you meet it
Dropping a bowling ball and a feather inside a giant vacuum chamber causes them to hit the floor at the exact same second.
Riders on a drop tower amusement ride experience a moment of weightlessness the instant the ride plunges downward.
In one sentence
Free fall is motion driven purely by gravity with no air resistance, causing all objects—regardless of weight—to drop and accelerate at the exact same rate.