FORCES FORCES

TYPES OF FORCES TYPES OF FORCES

FREE BODY DIAGRAMSFREE BODY DIAGRAMS

DETERMINING NET FORCEDETERMINING NET FORCE

FORCESFORCES A force is a push or pull acting upon A force is a push or pull acting upon

an objectan object Contact forces = FrictionContact forces = Friction TensionTension NormalNormal Air Resistance Air Resistance Applied force Applied force Spring force Spring force Distance forces = gravitational , electrical, Distance forces = gravitational , electrical, magnetic magnetic

TYPES OF FORCESTYPES OF FORCES Applied force = force applied to an

object by a person or other object Gravity force = weight = attractive

force between two objects Fgrav=m x g m=mass(kg)

g=9.8m/s2

Normal force = the support force exerted upon an object which is in contact with another stable object

TYPES OF FORCES TYPES OF FORCES Friction = force that opposes the = force that opposes the

sliding motion between two touching sliding motion between two touching surfacessurfaces Static friction = force that prevents two = force that prevents two

surfaces from sliding past each othersurfaces from sliding past each other Air resistance = special type of frictional = special type of frictional

force - acts on objects as they travel force - acts on objects as they travel through airthrough air

Tension Force = force which is = force which is transmitted through a string ,rope, transmitted through a string ,rope, cable or wire when it is pulled tight by cable or wire when it is pulled tight by forces acting from opposite endsforces acting from opposite ends

FREE BODY DIAGRAMSFREE BODY DIAGRAMS Used to show the relative size and Used to show the relative size and

direction of all forces acting upon an direction of all forces acting upon an object in a given situationobject in a given situation

Size of the arrow reflects the size of the Size of the arrow reflects the size of the forceforce

The direction of the arrow shows the The direction of the arrow shows the direction which the force is acting direction which the force is acting

All force arrows are labeled to show the All force arrows are labeled to show the exact type of force exact type of force

Represent the object with a box and draw Represent the object with a box and draw the force arrows from the box outwardthe force arrows from the box outward

FREE BODY DIAGRAMSFREE BODY DIAGRAMS

F app

F grav

F frict

F norm

There can be any number of forces acting on the object

Now do the practice problems work sheet.

Determining Net ForceDetermining Net Force Newton #1 = an object at rest tends = an object at rest tends

to stay at rest and an object in motion to stay at rest and an object in motion tends to stay in motion with the same tends to stay in motion with the same speed and in the same direction speed and in the same direction unless acted upon by an unless acted upon by an unbalanced force

Free body diagrams are used to determine if there is an unbalanced force in a given situation

Determining Net ForceDetermining Net Force F tens=1200N

F grav=800N

F air=600N

F grav=800N

F grav=50N

F frict=20N

F norm= 50N

The net force is the sum of all the forces that act on an object.See examples

Net Force - Net Force - examplesexamples

F app= 5N

F grav= 3 N

Ffrict=5N

F norm= 3N

F net = ?

F norm = 3 N

F grav = 3N

F frict= 5 N

F net = ?

Net Force - examplesNet Force - examples

B

A 50 N

200 N

If F net = 0 N Find the value for A and B