Force Calculator
Force calculator
Motion, weight, and signed net force in one workspace.
1 N = 1 kg·m/s²
InputsF = maSolve force • 2 known quantitiesLive
Net force
20 N
F = m × a with signed force and acceleration in one dimension.
Live
F = m × a
F = ma
Net force
20 N
Mass
4 kg
Acceleration
5 m/s²
Calculation steps
- Convert known values to SI: 4 kg and 5 m/s².
- F = m × a gives 20 N.
Model boundary: F = ma returns net external force, not impact force or one individual contact force. Weight mode uses a selected gravitational field; local Earth gravity varies.
Formula
Fnet = m x a; W = m x g; Fnet = sum of signed forces W = m \times g F_{net} = \sum_i F_i Symbol legend
| Symbol | Meaning | Unit | Copy |
|---|---|---|---|
F | Net force | N | |
m | Mass | kg | |
a | Acceleration | m/s^2 | |
W | Gravitational weight force | N | |
g | Gravitational field acceleration | m/s^2 |
- Motion mode solves net force, mass, or acceleration from exactly two known values.
- Weight mode multiplies mass by the selected gravitational acceleration, or solves mass from weight.
- Net-force mode adds signed one-dimensional forces; opposite directions use opposite signs.
- Inputs are converted to SI internally and returned in the selected display unit.
Example
Worked example: opposing forces
- 1 Choose the positive direction.
- 2 Enter +20 N in that direction and -12 N in the opposite direction.
- 3 Fnet = 20 + (-12) = 8 N
The net force is 8 N in the positive direction.
How
- Choose F = ma, Weight, or Net force.
- Select the unknown in motion or weight mode, then enter only the known values and units.
- For net force, enter positive and negative forces for opposite directions and optionally add mass for acceleration.
- Review the result, equivalent quantities, direction, and calculation steps.
Avoid
- Using grams instead of kilograms.
- Adding opposite-direction forces as if every force were positive.
- Treating mass and gravitational weight as the same quantity.
- Using F = ma as an impact-force formula without collision time or deformation data.
FAQ
Can acceleration be negative?
Yes, negative acceleration gives negative force in the chosen direction convention.
What unit is force output?
Choose newtons, kilonewtons, pound-force, or kilogram-force.
Does this include friction automatically?
No. In motion mode, enter the known net force. In net-force mode, enter friction as a signed force opposite the chosen positive direction.
Is weight the same as mass?
No. Mass is measured in units such as kilograms; weight is a force equal to mass times local gravitational acceleration.
Switch
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