Forces | Physics

force

a push or pull of one object on another object, measured in Newtons (N)

acceleration

changing speed of an object

normal force

the force "pushing back" like a table (R or N)

external force

push or pull acting ON an object

gravity

the force Fg about 10.0 m/s2

(Fgrav) is the mass of an object multiplied by a grav.

It is NOT just the acceleration of gravity

at rest

not moving, stopped

in motion

in motion, moving

the system

the object you are observing (the box in the force diagram)

act on

effect, change, push, pull, etc.

Newton's First Law : Inertia

Objects do not change their movement without a force acting on them

Newton's Second Law : F=ma

Newton (N) = kg • m/s2 F=ma force equals mass times acceleration

Newton's Third Law : Equal Reaction

If one object applies a force to a second object, then the second object will apply an equal and opposite force to the first object.

pull

move something towards

push

move something away

Fnet (net force)

total Force (which includes direction!) acting on an object

constant

not changing

Fnorm

Normal force, like a table or the road

Fgrav

Force of gravity (10.0 m/s2 • mass)

Fair

Force of air resistance

Fapp

Applied force, like a finger pushing a ball

Ffrict

the force that causes a moving object to slow down when it is touching another object

magnitude

size of something (shown in FBD by the length of the arrow)

vector

a magnitude with direction (Force is a vector)

contact force

force between objects that are touching (i.e. a push)

at a distance force

force between objects that are NOT touching (i.e. magnetic force)

mass

the amount of matter or stuff of an object (measure in kg, it is the same ANYWHERE!)

weight

the force of gravity on an object (measure in N, it changes depending on what planet you are on)

air resitance

force that is caused by air. The force acts opposite direction to an object moving through air

terminal velocity

the constant speed that a freely falling object reaches when the resistance (of the way which it is falling) stops further acceleration.

intertia

object keeps moving in a direction unless another forces acts on it

free body diagram

drawing that shows the forces acting on an object

balanced forces

object is at rest; total net force=0

unbalanced forces

object is moving; total net force>0