Newton’s Second Law Calculator

How it works

1. 1Choose what to solve for — Force, Mass, or Acceleration — using the “Solve for” selector.
2. 2Enter the two known values in your preferred unit system; the tool converts them to SI before computing.
3. 3The result is shown instantly using the exact rearrangement of F = m·a that you selected.

Use cases

• Physics students verifying homework on net force and acceleration in free-body diagrams.
• Engineers checking whether a drive motor can accelerate a known load within a required time.
• Science teachers demonstrating how doubling mass halves acceleration for a fixed force.

Frequently asked questions

What is Newton’s second law?

Newton’s second law states that the net force on an object equals its mass times its acceleration: F = m·a. Force is in newtons (N), mass in kilograms (kg), and acceleration in m/s². For example, a 5 kg box accelerating at 3 m/s² needs a net force of 5 × 3 = 15 N.

What are the three rearrangements of F = m·a?

The formula has three forms: (1) F = m·a to find force; (2) m = F ÷ a to find mass (undefined when a = 0); (3) a = F ÷ m to find acceleration (undefined when m = 0). This calculator covers all three.

Can I mix metric and imperial values?

No — use one consistent system. Select metric (kg, m/s², N) or imperial (lb, ft/s², lbf) with the toggle. The calculator converts inputs to SI internally, computes, then converts the result back to your chosen unit.