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Net Force, Mass & Acceleration

Solve F = ma for a positive mass using signed force and acceleration along one axis.

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Calculator inputs

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How to use this calculator

  1. Enter the known values in the units shown. Results update as you type.
  2. Where results are editable, change one to solve backwards. Lock a value to hold it fixed.
  3. Use the worked example to check the method. Reset restores the starting fields.

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Inputs and results stay in this browser tab. Bookify does not upload or store the values you enter.

Formula and method

A 2 kg object acted on by a net force of 10 N accelerates at 5 m/s². Reversing the force to −10 N gives −5 m/s² on the chosen axis.

Net force = mass × acceleration; acceleration = net force ÷ mass

Worked example

Enter these known values and leave the other values blank.

Positive mass
2 kg
Net force along the axis
10 N
Acceleration along the axis
5 m/s²

Assumptions and limitations

  • The mass is constant and positive. This is the classical one-axis form of Newton’s second law in an inertial reference frame.
  • Use the net force, meaning the sum of forces along the chosen axis. An individual applied force need not equal the net force when friction or other forces act.
  • Force and acceleration may be signed; with positive mass they point in the same direction along the axis. Zero force gives zero acceleration.
  • The g acceleration unit is standard gravity, exactly 9.80665 m/s². It is not a measurement of local gravity. Zero force and zero acceleration do not uniquely determine mass.

Common questions

Is force the same as weight?

Weight is one particular gravitational force. The force in F = ma is the net force after combining all forces along the axis.

Can I enter a negative acceleration?

Yes. The sign indicates direction relative to the chosen positive axis. It does not mean the mass is negative.

References

Bookify requires positive mass for the classical constant-mass F = ma model. The pound-force uses the exact international pound and standard gravity instead of the rounded captured factor. The poundal uses exactly one international pound-foot per second squared. Feet per second squared use exactly 0.3048 meters per second squared, replacing a rounded reciprocal factor.

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