Newton's Second Law Calculator — F = ma
Apply Newton's second law of motion: F = m × a. Enter any two of force (N), mass (kg), and acceleration (m/s²) and the calculator solves for the missing quantity, plus weight on Earth and impulse.
N
kg
m/s²
Net force in newtons
- 1
Mass
m = 10 kg = 10 - 2
Acceleration
a = 5 m/s² = 5 - 3
Force F = m × a
10 × 5 = 50
How does this calculator work?
Newton's second law: F = m × a. Net force (N) equals mass (kg) times acceleration (m/s²). Enter any two — for example 10 kg at 5 m/s² gives F = 50 N. The law applies to all classical (non-relativistic) mechanics and is the foundation of dynamics.
Formula
How this is calculated
Newton's second law of motion states that the net force acting on an object equals its mass times its acceleration: F = m × a. This is the central equation of classical mechanics: force (N = kg·m/s²) is the net external force pushing or pulling the object; mass (kg) is the object's inertia — its resistance to changes in motion; and acceleration (m/s²) is the rate of change of velocity in the direction of the net force.
Rearranging gives m = F / a (find an unknown mass from a measured force and acceleration) and a = F / m (find the acceleration a known net force produces on a known mass). The calculator reads whichever two fields are filled and derives the third; if all three are filled, force takes precedence and the result is verified.
Two derived quantities are also shown: weight on Earth (mass × 9.80665 m/s², the standard gravitational acceleration) and impulse (force × 1 second = change in momentum), which shows how much momentum the force imparts per second. Note that this applies only to classical (non-relativistic) mechanics — at speeds approaching the speed of light, relativistic corrections become significant.
Frequently asked questions
Newton's second law says the heavier an object is, or the more force you apply, the greater the acceleration. Specifically, acceleration equals net force divided by mass (a = F/m). Push the same mass harder and it accelerates more; push a heavier mass with the same force and it accelerates less.
The SI unit of force is the newton (N), defined as 1 kg·m/s². So 1 N accelerates 1 kg at 1 m/s². Common conversions: 1 N ≈ 0.2248 pounds-force (lbf); 4.448 N = 1 lbf.
Newton's second law is extremely accurate for everyday speeds and scales. It breaks down at relativistic speeds (a significant fraction of the speed of light), at quantum scales (subatomic particles), and in strong gravitational fields. For typical engineering and everyday problems it is essentially exact.
Also known as
TG we-Calculate Editorial Team. (2026). Newton's Second Law Calculator — F = ma [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/newtons-second-law-calculator
TG we-Calculate Editorial Team. "Newton's Second Law Calculator — F = ma." TG we-Calculate. 2026. https://we-calculate.com/calculator/newtons-second-law-calculator.
TG we-Calculate Editorial Team, "Newton's Second Law Calculator — F = ma," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/newtons-second-law-calculator
@misc{wecalculate_newtons_second_law_calculator, title = {Newton's Second Law Calculator — F = ma}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/newtons-second-law-calculator}}, year = {2026}, note = {TG we-Calculate} }
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