4 NEWTONS PROMBLEMS !!

Formulas：

F=ma   Fk=μkFn   Fs=μsFn

Equilibrium

There is no force when the force is balanced.

Assumptions:

-          no air resistance

-          no friction

-          a=0 ( ax=0 and ay=0 )

-          set positive axis

-          break down in to x and y components

-          Free Body Diagram

-          T1x=T2x

Inclines (Static) / Incline (Kinetic)

The object in on an incline surface, one is static has no acceleration and another one is kinetic with acceleration.

Inclines (Static) Assumptions:

-          no air resistance

-          FN  perpendicular to the surface

-          positive axis is the direction of acceleration

-          no acceleration

-          break down in to x and y components

-          Free Body Diagram

-          Fgx-f=0

-          FN-Fgy=0

Inclines (Kinetic)
Assumptions:

-          no air resistance

-          FN  perpendicular to the surface

-          positive axis is the direction of acceleration

-          break down in to x and y components

-          acceleration does not equal to zero

-          Free Body Diagram

-          FN-Fgy=0

-          Fgx-f=ma

Pulley

A pulley has two mass one is going up and one is going down, is used to change the direction of an applied force, the acceleration are the same.

Assumption:

-          pulley is frictionless

-          rope frictionless

-          no air resistance

-          Positive axis is the position of the

-          2 system, 2 Free Body Diagrams

-          T1=T2

-          Acceleration of the system is the same ay1 = ay2

-          break down in to x and y components acceleration

Trains

We assume the train as a whole.

Assumption

-          positive axis is the direction of acceleration

-          acceleration is constant

-          no air resistance

-          acceleration of the system is the same

-          ay = 0

-          3 Free Body Diagrams
-          T1y-T2y-Fg= 0