Calculate
How to use this calculator
Choose the formula (if there is more than one), choose what you want to find, then fill in the other values using the units shown. The calculator rearranges the formula, puts your numbers in, and shows every step.
How it's calculated
Newton's second law F = ma. Weight W = mg. Friction F = μR. Hooke's law F = ke. Force is in newtons (N), mass in kg and acceleration in m/s².
Worked example
A 5 kg trolley accelerates at 3 m/s². Force = 5 × 3 = 15 N.
Frequently asked questions
Which value of g should I use?
9.8 m/s² is standard. Some exams use 10 m/s². You can choose.
What is the difference between mass and weight?
Mass is the amount of matter (kg). Weight is the pull of gravity on it (N).
Related tools
Last updated October 2026. Results are for learning and guidance; always check important work. Calculations run in your browser and are not stored.