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Calculators/Newton's Second Law
Classical Mechanics

Newton's Second Law Calculator

Calculate force, mass or acceleration using F = ma. Supports Newtons, kilonewtons, pound-force, and g-force units. Full step-by-step working shown.

Solve for

F = m × a
Solving for F
Quick examples
Enter values above to calculate.

Newton's Second Law equations

Net force
F = ma
Solve for mass
m = F / a
Solve for acceleration
a = F / m
Weight
W = mg (g = 9.81 m/s²)
Impulse-momentum
F·t = m·Δv
Net force (momentum)
F = Δp / Δt

Newton's Second Law — F = ma

Newton's Second Law of Motion states that the net force on an object equals its mass times its acceleration: F = ma. This is arguably the single most important equation in classical mechanics — it is the bridge between kinematics (describing motion) and dynamics (explaining why things move as they do).

The law tells us three things: a larger force produces a larger acceleration; a more massive object requires a larger force to achieve the same acceleration; and force and acceleration always point in the same direction.

For the full derivation and all three of Newton's laws, see Newton's Laws of Motion and our dedicated F = ma article.

What is the difference between mass and weight?↓
Mass (kg) is the amount of matter in an object and is constant everywhere. Weight (N) is the gravitational force acting on that mass — it depends on local gravity. On the Moon, your mass is unchanged but your weight is 1/6 of your Earth weight.
What does net force mean?↓
Net force is the vector sum of all forces acting on an object. Newton's Second Law uses net force — if two 100N forces act in opposite directions, the net force is 0N and there is no acceleration, even though large forces are involved.
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