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Newton's second law is sometimes presented as a definition of force, i.e., a force is that which exists when an inertial observer sees a body accelerating. In order for this to be more than a tautology — acceleration implies force, force implies acceleration — some other statement about force must also be made.
The name 'zeroth law' was invented by Ralph H. Fowler in the 1930s, long after the first, second, and third laws were widely recognized. The law allows the definition of temperature in a non-circular way without reference to entropy, its conjugate variable .
The second law of thermodynamics is a physical law based on universal empirical observation concerning heat and energy interconversions. A simple statement of the law is that heat always flows spontaneously from hotter to colder regions of matter (or 'downhill' in terms of the temperature gradient).
Second law: In an inertial reference frame , the vector sum of the forces F on an object is equal to the mass m of that object multiplied by the acceleration a of the object: F → = m a → {\displaystyle {\vec {F}}=m{\vec {a}}} .
There are two main descriptions of motion: dynamics and kinematics.Dynamics is general, since the momenta, forces and energy of the particles are taken into account. In this instance, sometimes the term dynamics refers to the differential equations that the system satisfies (e.g., Newton's second law or Euler–Lagrange equations), and sometimes to the solutions to those equations.
Since the definition of acceleration is a = dv/dt, the second law can be written in the simplified and more familiar form: =. So long as the force acting on a particle is known, Newton's second law is sufficient to describe the motion of a particle.
Newton’s second law of motion states that the rate of change of momentum of an object is equal to the resultant force F acting on the object: =, so the impulse J delivered by a steady force F acting for time Δ t is: J = F Δ t . {\displaystyle \mathbf {J} =\mathbf {F} \Delta t.}
However, in mathematics Newton's laws of motion can be generalized to multidimensional and curved spaces. Often the term Newtonian dynamics is narrowed to Newton's second law m a = F {\displaystyle \displaystyle m\,\mathbf {a} =\mathbf {F} } .