Second Law of Motion
The second law defines a force mathematically. The force necessary to accelerate an object is equal to the mass m multiplied by the acceleration, a. That is:
F = m a
… where F is the force, measured in the unit Newtons (N), m is the mass, measured in the unit kilograms (kg), and a is the acceleration, measured in the unit meters per second2 (m/s2). Acceleration describes a change in velocity per unit of time – if a car changes from a velocity of 0 m/s to 10 m/s in the span of one second, then it has a velocity of 10 m/s2. The force necessary to accelerate a 5000kg car 10 m/s2 is equal to:
F = (5,000 kg) * (10 m/s2) = 50,000 Newtons
It is worth noting that the unit Newtons is equal to the unit kg*m/s2, that is, the unit of mass multiplied by the unit of acceleration.