Air Resistance and Drag
Moving through fluid creates a force opposing motion.
About this topic
Drag is the force opposing the motion of an object through a fluid. It increases with speed, cross-sectional area and fluid density, and depends on shape, approximately F = ½ρCdAv². Streamlined shapes reduce it.
Drag causes falling objects to reach terminal velocity and is why cars use more fuel at high speed, since the force grows with the square of speed, and the power needed grows with the cube. Doubling speed quadruples drag. Cyclists tuck in, aircraft have smooth wings, and trucks have deflectors to reduce it.
Example: a car at 30 m/s feels about four times the drag of the same car at 15 m/s. Following a lorry closely, called drafting, lowers the drag, as racing cyclists and geese know. Golf balls have dimples that actually reduce drag by keeping airflow attached longer. Parachutes, in contrast, are designed to increase drag.
Misconceptions: a heavy and a light object do not fall equally in air, because drag matters more for light objects. In the idealised problems we usually ignore drag, but real projectiles travel shorter distances and with asymmetrical paths because of it.
Key ideas
- Drag increases with speed and area
- Streamlined shapes reduce drag
- Balances weight at terminal velocity
Quick check
Use cases: where Air Resistance and Drag helps
- Homework: review the key idea behind Air Resistance and Drag before you start a problem set.
- Exam revision: use the quick check to test whether you can recall Air Resistance and Drag without notes.
- Visual learning: play with the interactive lab to see how Air Resistance and Drag changes when you adjust its inputs.
- Teaching a friend: explain Air Resistance and Drag in your own words, then compare your version with the key ideas.
The same laws describe car crashes, sports, satellites and everyday machines.
Frequently asked questions
What is Air Resistance and Drag?
Moving through fluid creates a force opposing motion.
What will I learn in Air Resistance and Drag?
Drag increases with speed and area. Streamlined shapes reduce drag. Balances weight at terminal velocity.
Is Air Resistance and Drag part of Physics?
Yes. It is one of 150 Physics topics on LearnViz HighSchoolEdu, with 3 key ideas, a live animation and a quick check.
Does the Air Resistance and Drag lab work on a phone or tablet?
Yes. The animation resizes to fit your screen and supports touch, so you can drag, tap and slide with your finger.
How should I study Air Resistance and Drag?
Read the summary and key ideas first, play with the interactive lab to see the idea in motion, then answer the quick check. If you get a question wrong, go back to the key idea it tests.
Do I need an account, and is my progress saved?
No account is needed. Marking a topic as learned is saved in your own browser, so it stays on that device and is not sent to a server.