# Fundamental Physics/Force

(Redirected from Force)

Force is a physical entity interacts with matter to perform a task . For example, a person uses his strength to push a door to open . Force represents the strength used to open the door .

Force is denoted as F measures in unit Newton N

## Motion Force

Motion Force is defined as the force interacts with matter to make matter go in motion moving from one place to another place . Motion Force is denoted as Fa measured in Newton N

According to Newton's 2 law, force causes matter to move from one place to another place can be calculated by

${\displaystyle F_{a}=ma}$

With

${\displaystyle F_{a}}$  . Motion Force
${\displaystyle m}$  . Mass of matter
${\displaystyle a}$  . Acceleration

## Impulse

Impulse is defined as the force causes a mass to move at a speed . According to Newton's 2 law, force causes matter to move from one place to another place can be calculated by

${\displaystyle F_{p}=ma=m{\frac {v}{t}}={\frac {p}{t}}}$

With

${\displaystyle F_{p}}$  . Impulse
${\displaystyle m}$  . Mass of matter
${\displaystyle a}$  . Acceleration
${\displaystyle v}$  . Speed
${\displaystyle p=mv}$  . Moment

## Opposition Force

Force matter generates to oppose the interacting force . Opposition force is denoted as F- measured in Newton N calculated by

${\displaystyle F_{-}=-F}$

With

${\displaystyle F_{-}}$  . Opposite Force
${\displaystyle F}$  . Interacting Force

## Elastic Force

Fk is the force that responds to the load on the spring

An elastic force acts to return a spring to its natural length. An ideal spring is taken to be massless, frictionless, unbreakable, and infinitely stretchable. Such springs exert forces that push when contracted, or pull when extended, in proportion to the displacement of the spring from its equilibrium position.

This linear relationship was described by Robert Hooke in 1676, for whom Hooke's law is named. If ${\displaystyle \Delta y}$  is the displacement, the force exerted by an ideal spring equals:

${\displaystyle {\vec {F}}=-k\Delta {\vec {y}}}$

where

${\displaystyle k}$  is the spring constant (or force constant), which is particular to the spring
The minus sign (-) accounts for the tendency of the force to act in opposition to the applied load.
${\displaystyle \Delta {\vec {y}}}$  . Vertical Displacement

## Friction Force

Friction is a surface force that opposes relative motion. The frictional force is directly related to the normal force that acts to keep two solid objects separated at the point of contact. There are two broad classifications of frictional forces: static friction and kinetic friction.

### Static friction force

The static friction force (${\displaystyle F_{\mathrm {sf} }}$ ) will exactly oppose forces applied to an object parallel to a surface contact up to the limit specified by the coefficient of static friction (${\displaystyle \mu _{\mathrm {sf} }}$ ) multiplied by the normal force (${\displaystyle F_{N}}$ ). In other words, the magnitude of the static friction force satisfies the inequality:

${\displaystyle 0\leq F_{\mathrm {sf} }\leq \mu _{\mathrm {sf} }F_{\mathrm {N} }.}$

### Kinetic friction force

The kinetic friction force (${\displaystyle F_{\mathrm {kf} }}$ ) is independent of both the forces applied and the movement of the object. Thus, the magnitude of the force equals:

${\displaystyle F_{\mathrm {kf} }=\mu _{\mathrm {kf} }F_{\mathrm {N} },}$

where ${\displaystyle \mu _{\mathrm {kf} }}$  is the coefficient of kinetic friction. For most surface interfaces, the coefficient of kinetic friction is less than the coefficient of static friction.

## Pressure Force

Pressure (symbol: p or P) is the force applied perpendicular to the surface of an object per unit area over which that force is distributed.Force acts perpendicular on a surface's area . Presure Force is denote as F_A measured in Newton N calculated by

${\displaystyle F_{A}={\frac {F}{A}}}$

With

${\displaystyle F_{A}}$  . Pressure Force
${\displaystyle A}$  . Area of the surface

## Gravitational Force

The force of attraction between two mass separate at a distance . Gravity Force is denoted as Fg measured in Newton N

${\displaystyle F_{g}=m{\frac {MG}{r^{2}}}}$

With

${\displaystyle F_{g}}$
${\displaystyle m}$
${\displaystyle M}$
${\displaystyle r}$

## Centripetal Force

For an object accelerating in circular motion, the unbalanced force acting on the object equals:

${\displaystyle F_{r}=m{\frac {v^{2}}{r}}=mr\omega ^{2}\,.=mr({\frac {2\pi }{T}})^{2}\,}$

With

${\displaystyle F_{r}}$  . Centripetal Force
${\displaystyle m}$  . Mass
${\displaystyle v}$  . Speed
${\displaystyle r}$  . Radius of circle

where ${\displaystyle m}$  is the mass of the object, ${\displaystyle v}$  is the velocity of the object and ${\displaystyle r}$  is the distance to the center of the circular path and ${\displaystyle \scriptstyle {\hat {r}}}$  is the unit vector pointing in the radial direction outwards from the center. This means that the unbalanced centripetal force felt by any object is always directed toward the center of the curving path. Such forces act perpendicular to the velocity vector associated with the motion of an object, and therefore do not change the speed of the object (magnitude of the velocity), but only the direction of the velocity vector. The unbalanced force that accelerates an object can be resolved into a component that is perpendicular to the path, and one that is tangential to the path. This yields both the tangential force, which accelerates the object by either slowing it down or speeding it up, and the radial (centripetal) force, which changes its direction.

## Electrostatic Force

The attraction force of negative charge attracts the positive charge calculated by Coulom's law

${\displaystyle F={\frac {q_{1}q_{2}}{4\pi \varepsilon _{0}\,r^{2}}}=K{\frac {q_{1}q_{2}}{r^{2}}}}$

Where:

${\displaystyle F\ }$  is the magnitude of the force exerted,
${\displaystyle q_{1}\ }$  is the charge on one body,
${\displaystyle q_{2}\ }$  is the charge on the other body,
${\displaystyle r\ }$  is the distance between them,
${\displaystyle \varepsilon _{0}\ }$  is the electric constant or permittivity of free space or permittivity of the vacuum. It is 8.854×10−12 C2 :N-1 m-2 (also F m-1)
${\displaystyle K={\frac {1}{4\pi \varepsilon _{0}\,}}}$

## Electrodynamic Force

${\displaystyle F_{E}=qE}$

## Electromagnetomotive Force

It is noted that when a charge in motion travels through a magnetic field of a magnet. The charge's magnetic field and magnet's magnetic field interact to bend magnet's magnetic field upward or downward . For positive charge bends magnet's magnetic field upward , negative charge bends magnet's magnetic field downward

For positive charge ${\displaystyle F_{B}=+qvB}$  . For negative charge ${\displaystyle F_{B}=-qvB}$  . Force interacts with electric charge to creates Magnetic Field

${\displaystyle F_{B}=\pm qvB}$

With

${\displaystyle F_{B}}$  . Electrodynamic Force
${\displaystyle q}$  . Electric Charge
${\displaystyle B}$  . Electric Field
${\displaystyle v}$  . speed

From above,

${\displaystyle B={\frac {F_{B}}{\pm qv}}}$

## Electromagnetic Force

Electromagnetic force acts on an electric charge is the sum of 2 forces Electrostatic force and Electromagnetomotive force

${\displaystyle F_{EB}=F_{E}+F_{B}=qE\pm qvB=q(E\pm vB)}$

With

${\displaystyle F_{EB}}$
${\displaystyle F_{E}}$  . Electric Field Force
${\displaystyle F_{B}}$  . Electromagnetic Field Force
${\displaystyle Q}$  . Electric charge
${\displaystyle E}$  . Electric Field
${\displaystyle B}$  . Magnetic Field
${\displaystyle v}$  . Speeed

## Equilibrium

### Free fall

Free fall without air resistance
${\displaystyle F=mg={\frac {mMG}{h^{2}}}}$
${\displaystyle h={\sqrt {\frac {mMG}{F}}}}$
Free fall with air resistance
${\displaystyle F_{p}=F_{\theta }cos\theta =ma}$
${\displaystyle F_{g}=F_{\theta }sin\theta =mg}$
${\displaystyle F_{\theta }={\sqrt {F_{p}^{2}+F_{g}^{2}}}=m{\sqrt {a^{2}+g^{2}}}}$
${\displaystyle \theta =Tan^{-1}{\frac {F_{g}}{F_{p}}}=Tan^{-1}{\frac {g}{a}}}$

### Floatingl

${\displaystyle F_{p}=F_{g}}$
${\displaystyle {\frac {mv}{t}}=mg}$
${\displaystyle a=g={\frac {MG}{h^{2}}}}$
${\displaystyle h=}$
${\displaystyle v=gt}$
${\displaystyle t={\frac {v}{g}}}$