Newton’s First Law: (The law of inertia). An object at rest tends to stay at rest, and an object in motion tends to stay in motion in a straight line and at constant speed unless acted upon by an unbalanced force.

Newton’s Third Law: (The law of action and reaction or opposing forces). For every force there is an equal and opposite force.

Conservation of Energy: Conservation of energy states that the total amount of energy (including potential energy) in an isolated system remains constant. In other words, energy can be converted from one form to another, but it cannot be created or destroyed. In modern physics, all forms of energy exhibit mass and all mass is a form of energy.

Kinetic energy (SI unit: the joule) is energy that a body possesses as a result of its motion. It is formally defined as the work needed to accelerate a body from rest to its current velocity. Having gained this energy during its acceleration, the body maintains this kinetic energy unless its speed changes. Negative work of the same magnitude would be required to return the body to a state of rest from that velocity.

Potential energy is energy that is "captured" in an object, with the potential to be released. There are various different types of potential energy. Many of these – such as gravitational, elastic, or electrical potential energy – arise from the relative positions or configurations of objects. The potential energy may then be defined as the work that must be done against a particular force – in these examples, gravitational, electrical or elastic force – so as to achieve that configuration. Chemical potential energy is slightly different, at least in its macroscopic manifestation: it is the energy that is available for release from chemical reactions (for example, by burning a fuel).

Friction: Friction is the force that opposes the relative motion or tendency of such motion of two surfaces in contact. It is not, however, a fundamental force, as it originates from the electromagnetic forces and exchange force between atoms. In situations where the surfaces in contact are moving relative to each other, the friction between the two objects converts kinetic energy into heat (atomic vibrations). Friction between solid objects and fluids (gases or liquids) is called fluid friction. Surface roughness contributes to friction by increasing surface area.

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Force: In physics, a classical force is a name given to a net influence that causes a free body with mass to accelerate. A net (or resultant) force that causes such acceleration may be the non-zero additive sum of many different forces acting on a body.