Newton's Second Law or the Law of Dynamics states that the force acting on an object is equal to the mass of the object multiplied by the acceleration it undergoes:
$$\vec{F}=m\vec{a}$$
where,
mβ mass of the object
aβ acceleration.
In the International System of Units (SI), the unit of force is the newton (N). One newton is the force that gives a mass of 1 kg an acceleration of 1 m/s2.
Newton's Second Law can also be expressed as:
$$\vec{F}=\frac {d\vec{p}}{dt}$$
where,
dpβ change in momentum
dtβ time interval for the change in momentum.
In this more general form, the law remains valid in special relativity.
It states that force equals mass times acceleration.
The net force on an object determines how much it accelerates for a given mass.
The momentum form is the more general version and stays valid in special relativity.