What is Newton's second law?

Newton's second law states that the net force acting on an object equals its mass multiplied by its acceleration: F = m × a. Force is measured in Newtons (N), mass in kilograms (kg), and acceleration in meters per second squared (m/s²).

What is the difference between mass and weight?

Mass is the amount of matter in an object (kg), while weight is the force exerted on that mass by gravity (N). On Earth, weight = mass \xc3\x97 9.80665 m/s\xc2\xb2. An object with a mass of 1 kg has a weight of about 9.807 N.

What is a pound-force (lbf)?

A pound-force is the gravitational force exerted on a mass of one avoirdupois pound at standard Earth gravity. 1 lbf = 4.4482216 N. It is distinct from pound-mass (lb), which is a unit of mass.

What does g mean as an acceleration unit?

The symbol g (lowercase) denotes standard Earth gravitational acceleration: 9.80665 m/s\xc2\xb2. An acceleration of 3g means the object accelerates at 3 \xc3\x97 9.80665 = 29.42 m/s\xc2\xb2.

How do you calculate force?

Multiply mass by acceleration: F = m × a. For example, a 10 kg object accelerating at 2 m/s² needs a force of 10 × 2 = 20 N. Enter any two of force, mass, and acceleration and the calculator solves for the third.

Force Calculator

Name: Force Calculator
Availability: InStock
Author: Nham Vu

Given any two of Force, Mass, and Acceleration, this calculator solves for the third using Newton's second law F = m × a with full multi-unit support.

Force Calculator

Solve for

Mass

Acceleration

Enter two known values on the left to compute the third.

F = m × a — Newton’s Second Law

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Summary

Given any two of Force, Mass, and Acceleration, this calculator solves for the third using Newton's second law F = m × a with full multi-unit support.

How it works

Choose what you want to calculate: Force, Mass, or Acceleration.
Enter values for the other two quantities using the input fields.
Select the appropriate unit for each quantity from the dropdown menus.
Click Calculate to see the result along with cross-unit conversions.
Click Reset to clear all inputs and start over.

Use cases

Verify force calculations in physics homework using Newton's second law.
Determine how much force a rocket engine must produce to accelerate a given payload.
Convert between SI and imperial force/mass units in engineering problems.
Understand the relationship between weight (force due to gravity) and mass.

Frequently Asked Questions

Last updated: 2026-06-09 · Reviewed by Nham Vu