Newton's second law, made practical

Find the missing force, mass, acceleration, and related values.

Enter the quantities you know. FISMA fills the rest using compatible SI units, so the relationships stay visible while you work.

F = m a

Interactive calculator

Known values

Type numbers into any fields. Calculated fields are labelled automatically; edit a calculated value to make it one of your known values.

Core: force equals mass times acceleration

Force F N newtons

Mass m kg kilograms

Acceleration a m/s² metres per second squared

Motion, gravity, and energy

Velocity v m/s metres per second

Momentum p kg m/s p = mv

Kinetic energy KE J KE = 1/2 mv²

Gravity g m/s² standard Earth gravity

Weight W N W = mg

Impulse, work, and power

Time t s seconds

Impulse J N s J = Ft

Distance d m metres

Work E J E = Fd

Power P W P = E/t or P = Fv

Enter at least two related values to begin.

Formula sheet

Reference

All calculations use SI units. The same letter can mean different things depending on context, so check the unit as well as the symbol.

F: Force, measured in newtons N.
m: Mass, measured in kilograms kg. A lowercase m can also mean metres when used as a unit.
a: Acceleration, measured in metres per second squared, m/s².
v: Velocity, measured in metres per second, m/s.
p: Momentum, measured in kilogram metres per second, kg m/s.
KE: Kinetic energy, measured in joules J.
g: Gravitational field strength, measured in m/s². Standard Earth gravity is 9.80665 m/s².
W: Weight when used as a quantity, measured in newtons. As a unit, W means watt, the unit of power.
t: Time, measured in seconds s.
J: Impulse when used as a quantity, measured in newton seconds, N s. As a unit, J means joule.
d: Distance, measured in metres m.
E: Work or transferred energy, measured in joules J.
P: Power, measured in watts W. One watt is one joule per second.