Final answer:
Newton's second law, in terms of momentum, states that the net external force is equal to the rate of change of momentum, mathematically expressed as Fnet = dp/dt. When mass is constant, it simplifies to Fnet = ma.
Step-by-step explanation:
Newton's second law in terms of momentum states that the net external force acting on an object is equal to the rate of change of its momentum (p). This can be mathematically expressed in the form of a differential equation as Fnet = dp/dt, where p is the momentum (p = mv), m is the mass, v is the velocity, and t is time.
If mass is constant, the equation can be simplified using the definition of acceleration (a = dv/dt) to obtain Fnet = m dv/dt, which is the classic form of Newton's second law expressed as Fnet = ma.