Force Calculator (Newton's Second Law)

F = ma

Force (N) = Mass (kg) × Acceleration (m/s²). The Newton is defined as the force required to accelerate a 1kg mass at 1 m/s². Gravity on Earth accelerates objects at g = 9.81 m/s², so a 10kg object has a gravitational force (weight) of 98.1N.

Weight vs Mass

Mass is the amount of matter in an object (kg) and never changes. Weight is the gravitational force on that mass (N) and varies with gravity. Your mass on the Moon is the same as on Earth. Your weight on the Moon is 1/6 of your Earth weight.

Applications

Calculating braking force needed to stop a vehicle. Finding the thrust required to accelerate an aircraft. Determining the tension in a rope supporting a weight. Any problem where force, mass, and acceleration interact.

Units and Significant Figures

Science calculations require consistent units throughout. Mixed units (some in metres, some in centimetres) are the most common source of errors. Always check: are all values in SI units (metres, kilograms, seconds, kelvin) before substituting into formulas? The number of significant figures in an answer should not exceed the least precise measurement used in the calculation. When quoting a result, scientific notation (e.g. 3.7 x 10 to the power 4) avoids ambiguity about significant figures and