Newton's Second Law Calculator (F = ma)
Solve F = m·a for any of the three variables with built-in unit conversions.
Leave the unknown blank and fill the other two.
Formula
In SI, F in newtons (N), m in kilograms (kg), a in metres per second squared (m/s²).
How to use
- Leave one field blank — that's the variable the tool will solve for.
- Enter the other two and pick the units.
- Press Calculate.
Physics behind F = ma
Newton's second law is the quantitative statement of how force, mass and motion are related. It says that the net (total) force on an object equals its mass multiplied by the acceleration it experiences. Force is a vector — so is acceleration — and F = ma applies component by component.
For a constant mass, doubling the net force doubles the acceleration. For a fixed force, doubling the mass halves the acceleration. Rockets and jet engines rely on this law: propellant is expelled backwards with a large force, and Newton's third law applies an equal and opposite force on the rocket, giving it the forward acceleration.
Worked example
m = 10 kg, a = 2 m/s²
F = m·a = 10 × 2 = 20 N
Related tools
FAQs
What is Newton's second law?
Net force equals mass × acceleration — F = m·a.
What is 1 N in everyday terms?
About the weight of a 100-gram apple on Earth.
Does this work with pound-force?
Yes — select lbf in the force dropdown.