Force calculator — Newton’s second law
Newton’s second law is one of the foundations of mechanics, relating the force on an object to its mass and acceleration. This calculator applies F = m × a and rearranges it so you can solve for whichever quantity you do not know — force, mass, or acceleration — making it handy for physics homework, engineering estimates and lab work.
How it works
The law states that the net force on an object equals its mass times its acceleration. Choose what to solve for and the tool uses the matching form:
- Force: F = m × a
- Mass: m = F ÷ a
- Acceleration: a = F ÷ m
Enter the two known quantities in SI units — mass in kilograms (kg), acceleration in metres per second squared (m/s²) — and the result appears in newtons (N) for force, or the appropriate unit for mass or acceleration. One newton is the force that accelerates 1 kg at 1 m/s².
Example
A 5 kg crate pushed with an acceleration of 2 m/s² experiences a net force of F = 5 × 2 = 10 N. Conversely, if a 10 N force acts on that same 5 kg crate, its acceleration is a = 10 ÷ 5 = 2 m/s².
| Solve for | Known values | Result |
|---|---|---|
| Force | m = 5 kg, a = 2 m/s² | 10 N |
| Mass | F = 20 N, a = 4 m/s² | 5 kg |
| Acceleration | F = 12 N, m = 3 kg | 4 m/s² |
Every calculation runs locally in your browser — nothing is uploaded.