Calculators
Force Calculator
Solve force, mass, or acceleration with F = ma.
Use Newton's second-law relationship F = ma to calculate net force, mass, or acceleration. Signed force and acceleration can represent opposite one-dimensional directions.
Calculated force
6 N
F = ma
This uses net force and classical mechanics. It does not automatically add individual forces such as gravity, friction, drag, tension, or normal force.
About This Tool
Newton's second law connects an object's net force, mass, and acceleration. For constant mass in classical mechanics, the relationship is F = ma: the net force equals mass multiplied by acceleration. This calculator solves that relationship for force, mass, or acceleration and converts common metric and imperial units. Signed force and acceleration values can represent opposite directions along a chosen one-dimensional axis, and calculations stay in your browser.
How To Use It
- Choose whether to solve for net force, mass, or acceleration.
- Enter the two known quantities and select their units. Mass must be positive; force and acceleration may be signed for one-dimensional direction.
- Choose the desired result unit and review the formula displayed with the answer.
- Use the net force acting on the object. If several forces act at once, combine them appropriately before using this simplified one-dimensional calculator.
Examples
Basic force
A 2 kg object accelerating at 3 m/s² requires a net force of F = 2 × 3 = 6 N.
Standard gravity
A 1 kg mass multiplied by standard gravitational acceleration 9.80665 m/s² gives 9.80665 N. This numerical product is useful for learning the relationship, although actual weight situations depend on the physical context.
Find acceleration
A 12 N net force acting on a 4 kg mass gives a = 12 ÷ 4 = 3 m/s².
Opposite direction
With a positive mass, a negative net force produces a negative acceleration relative to the coordinate direction you chose.
Useful Notes
Newton's second law
For a constant-mass object in classical mechanics, net force is F = ma. Rearranging gives m = F/a and a = F/m.
Use net force
F in this equation is the vector sum of all external forces, not necessarily one individual push or pull. Friction, gravity, drag, tension, and normal forces may need to be included when they matter to the problem.
Units
The SI force unit is the newton (N), equal to kg·m/s². The calculator supports newtons, kilonewtons, pounds-force, kilograms, grams, pounds, m/s², ft/s², and standard gravity g.
Direction and signs
Force and acceleration are vectors. In one dimension, positive and negative signs can represent opposite directions. Mass remains positive.
Model limitations
This calculator uses the constant-mass classical relationship F = ma in one dimension. It does not model changing-mass systems, relativistic motion, rotational dynamics, or automatically resolve multiple vector components.
FAQ
What does F = ma mean?
It means an object's net force equals its mass multiplied by its acceleration for the standard constant-mass form of Newton's second law.
What is one newton?
One newton is the force that produces an acceleration of 1 m/s² on a mass of 1 kg, so 1 N = 1 kg·m/s².
Can force be negative?
Yes. In a one-dimensional coordinate system, a negative force indicates that the net force points opposite to the direction defined as positive.
Is mass in pounds the same as pounds-force?
No. Pound (lb) is used here as a mass unit, while pound-force (lbf) is a force unit. The calculator keeps these quantities separate.
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