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Force Calculator

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Enter any two of mass, acceleration, and force - based on Newton's second law - the third is calculated automatically.

Force Calculator

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Force =
30 N
Fill in exactly two values, and leave the one you want to solve for blank.

The formula

Force = Mass x Acceleration (Newton's Second Law: F = ma)
Example

A 10 kg object accelerating at 3 m/s²: force = 10 x 3 = 30 newtons.

Step-by-step guide

  1. Fill in any two values - mass, acceleration, or force - and leave the third blank.
  2. Read the calculated result.

Why the same force accelerates different masses differently

Newton's second law directly explains a familiar intuition: pushing a shopping cart and pushing a car with the same force produces very different results, because acceleration equals force divided by mass. A heavier object needs more force to achieve the same acceleration as a lighter one - this single, simple equation underlies an enormous range of everyday and engineering physics, from calculating rocket thrust to designing vehicle brakes.

Common mistakes

Confusing weight (a force, mass x gravity) with mass itself - mass is constant everywhere, but weight changes depending on local gravity, like on the Moon versus Earth.
Using pounds (a unit of force in the imperial system) as if it were a mass unit - this causes confusion when applying F=ma, which expects mass in kilograms in the standard SI form of the equation.

Frequently asked questions

What is Newton's second law, in plain language?

It states that the force needed to accelerate an object is directly proportional to its mass and the acceleration desired - heavier objects need more force for the same acceleration, and greater acceleration needs more force for the same mass.

What's the difference between mass and weight?

Mass measures the amount of matter in an object and stays constant everywhere. Weight is the force of gravity acting on that mass (Weight = mass x gravity), which is why the same object weighs less on the Moon despite having identical mass.

What unit is force measured in?

Newtons (N) in the SI system - one newton is defined as the force needed to accelerate a 1 kg mass at 1 meter per second squared.

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