Dynamics and Newton's Laws of Motion

Vocabulary flashcards covering the definitions of fundamental dynamics concepts, types of forces, and Newton's three laws of motion.

Dynamics

A branch of mechanics which deals with the forces that give rise to motion.

Kinematics

A branch of mechanics that describes how objects move without describing the force that caused the motion.

Force

A vector quantity defined as that which changes the velocity of an object.

External force

A force that lies outside of the system being considered.

Contact Force

A force in which one object has to be in contact with another to exert a force on it, such as a push or a pull.

Tension ($\vec{T}$)

The force on a string or chain tending to stretch it.

Normal force ($\vec{F}_N$)

The force which acts perpendicular to a surface which supports an object.

Weight ($\vec{W}$)

The force with which gravity pulls downward upon an object, equal to the gravitational force on the body and given as $\vec{W} = m\text{g}$.

Frictional force ($\vec{f}$)

The force on a body when the body slides or attempts to slide along a surface, which is always parallel to the surface and directed so as to oppose the motion of the body.

Net force ($\vec{F}_{net}$)

The vector sum of all force vectors that act on an object, expressed as $\vec{F}_{net} = \sum_{i=1}^{n} \vec{F}_i = \vec{F}_1 + \vec{F}_2 + \dots + \vec{F}_n$.

Newton’s First Law

The law stating that if no net force acts on a body ($\vec{F}_{net} = 0$), then the body's velocity cannot change (it cannot accelerate); if it was moving, it will remain in motion in a straight line with the same constant velocity.

Newton’s Second Law

The law stating that if a net external force $\vec{F}_{net}$ acts on an object with mass $m$, the force will cause an acceleration $\vec{a}$ in the same direction as the force, expressed as $\vec{F}_{net} = m\vec{a}$.

Newton’s Third Law

The law stating that the forces two interacting objects exert on each other are always exactly equal in magnitude and opposite in direction ($\vec{F}_{1\rightarrow 2} = -\vec{F}_{2\rightarrow 1}$).