S2.4 Classification of forces
- To make use of Newton’s 2nd law, the equation
specifying the acceleration, needs to be augmented by an equationspecifying the force.
Nature’s forces fall into three categories: fundamental, phenomenological and fictitious.
[A] Fundamental forces
- These are forces of interaction between elementary constituents of the
universe:
- gravitational force, between point masses
- electrostatic force, between point charges
- some others
- They are fully specified by some quantitatively explicit force law.
- Forward reference: S2.11 and S2.12
[B] Phenomenological forces
These are forces of interaction between macroscopic portions of matter.
- They represent the aggregate effects of fundamental forces.
- They can generally be described only by equations containing empirically-determined constants.
- Forward reference: S2.8
[C] Fictitious forces
- These are forces we invent to make sense of our experience in non-inertial reference frames.
- Forward reference: S2.13
Learning Resources
![]() | HRW Chapter 5.7, 6.5 |