Drag (physics)

What is Drag?

Drag is a gentle push that happens when something moves through air, water, or any other fluid. Imagine riding a bicycle — you feel the wind pushing back on you. That push is called drag. It works against the motion of anything moving through a fluid, helping it slow down.

How Drag Changes with Speed

When something moves slowly, drag changes a little bit as it speeds up. But when it moves really fast, drag grows much quicker! Scientists use something called the Reynolds number to study how fluids move around objects. This helps them predict how much drag there will be.

Everyday Examples

You can see drag in many places. Cars, airplanes, and boats all feel this push back from the air or water. Even in sports, drag affects how balls, frisbees, and arrows fly through the air. Swimmers and runners also need extra energy to push through the drag around them.

Types of Drag

There are a few kinds of drag. One type, called form drag, depends on the shape of the object. Another, skin friction drag, is caused by the rub between the fluid and the object's surface. For airplanes, there are also special types like lift-induced drag and wave drag, which help explain how wings and fast-moving planes behave.