Category: Electrical
Calculator
Example Data Table
| Object | Mass kg | Speed m/s | Cd | Area m² | Drag force N | Terminal speed m/s |
|---|---|---|---|---|---|---|
| Small sensor pod | 2.50 | 20 | 0.82 | 0.030 | 6.03 | 40.5 |
| Ball shaped part | 0.145 | 30 | 0.47 | 0.0042 | 1.09 | 34.3 |
| Flat cover plate | 1.00 | 15 | 1.17 | 0.250 | 40.3 | 7.40 |
Formula Used
Drag force: Fd = 0.5 × ρ × Cd × A × v²
Weight: W = m × g
Net force: Fnet = W − Fd
Acceleration: a = Fnet ÷ m
Terminal velocity: Vt = √(2mg ÷ ρCdA)
Dynamic pressure: q = 0.5 × ρ × v²
Reynolds number: Re = ρ × v × L ÷ μ
Impact speed with drag: v = Vt × √(1 − e−2gh/Vt²)
How to Use This Calculator
- Enter the object mass and choose its unit.
- Enter the current falling speed.
- Add the frontal area facing the airflow.
- Select a shape preset or enter a custom drag coefficient.
- Check air density, gravity, height, length, and viscosity.
- Press Calculate to view drag, acceleration, and terminal speed.
- Use CSV or PDF buttons to save the result.
Detailed Article
Understanding Air Resistance
A falling object does not move through empty space. It pushes air aside. The air pushes back. That push is drag force. At low speed, drag can be small. At higher speed, drag rises quickly. This calculator uses the common quadratic drag model. It is useful for balls, tools, packages, drones, test weights, and many outdoor objects.
Why Terminal Speed Matters
Weight pulls the object downward. Drag acts upward while the object falls. Net force is the difference between weight and drag. When both forces become equal, acceleration becomes zero. The object then falls at terminal speed. This value helps designers compare shapes, safety risks, and drop test results. It also helps estimate impact speed before detailed simulation.
Inputs That Control Drag
Air density changes with temperature, altitude, and humidity. The drag coefficient depends on shape and surface finish. Frontal area is the projected area facing the air. Velocity is the current falling speed. Mass controls weight and acceleration. Gravity may change for special locations. Characteristic length and air viscosity are optional. They estimate Reynolds number for flow review.
Electrical Use Case
Electrical teams may use this page during enclosure, sensor, cable drop, and drone payload studies. A falling outdoor part can damage conductors, panels, lamps, or support hardware. Air drag affects fall speed and impact energy. It also helps size protective covers and test fixtures. The method is still mechanical. The category is useful when electrical equipment is involved.
Practical Notes
The result is an engineering estimate. It assumes steady air, constant drag coefficient, and vertical motion. Wind, spin, tumbling, changing posture, and parachute effects can change results. Use measured drag data when available. For critical safety work, compare this estimate with standards, experiments, or a specialist review.
Reading The Results
Drag force shows the upward air load at the chosen speed. Net force shows the remaining downward force. Acceleration shows how fast speed is changing. Dynamic pressure shows air pressure caused by motion. Terminal velocity shows the limiting speed. Reynolds number helps judge whether the flow is slow, transitional, or turbulent.
Use the example table to test units first. Then adjust one input at a time. This makes each design comparison easier to understand clearly.
FAQs
What is air resistance?
Air resistance is the force created when air pushes against a moving object. For a falling object, this force acts upward and reduces downward acceleration.
Why does drag increase with speed?
The quadratic drag model uses velocity squared. Doubling speed can create about four times the drag, when other values stay constant.
What is drag coefficient?
Drag coefficient is a shape factor. Smooth, streamlined shapes have low values. Flat or blunt shapes usually have higher values.
What is terminal velocity?
Terminal velocity is the speed where drag force equals weight. At that point, net acceleration becomes zero under the same conditions.
Why is frontal area important?
Frontal area is the area facing the airflow. Larger area creates more drag and usually lowers terminal velocity.
Can this calculator handle imperial units?
Yes. Several input units are converted internally to metric values. Results are then shown in standard engineering units.
Is this result exact?
No. It is an estimate. Wind, tumbling, spin, surface texture, and changing air density can change the real falling behavior.
Why include Reynolds number?
Reynolds number helps review flow behavior around the object. It gives extra context for drag assumptions and testing decisions.