Download FORCES

FORCES
TYPES OF FORCES
FREE BODY DIAGRAMS
DETERMINING NET FORCE
FORCES
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A force is a push or pull acting upon an
object
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Contact forces = Friction
Tension
Normal
Air Resistance
Applied force
Spring force
Distance forces = gravitational , electrical,
magnetic
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TYPES OF FORCES
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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
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Friction = force that opposes the sliding
motion between two touching surfaces
Static friction = force that prevents two
surfaces from sliding past each other
 Air resistance = special type of frictional force
- acts on objects as they travel through air
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Tension Force = force which is transmitted
through a string ,rope, cable or wire when
it is pulled tight by forces acting from
opposite ends
FREE BODY DIAGRAMS
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Used to show the relative size and direction of all
forces acting upon an object in a given situation
Size of the arrow reflects the size of the force
The direction of the arrow shows the direction
which the force is acting
All force arrows are labeled to show the exact
type of force
Represent the object with a box and draw the
force arrows from the box outward
FREE BODY DIAGRAMS
F norm
F frict
F app
F grav
There can be any number of forces acting on the object
Now do the practice problems work sheet.
Determining Net Force
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Newton #1 = an object at rest tends to
stay at rest and an object in motion tends
to stay in motion with the same speed and
in the same direction unless acted upon by
an unbalanced force
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Free body diagrams are used to determine
if there is an unbalanced force in a given
situation
Determining Net Force
F norm= 50N
F tens=1200N
F frict=20N
F air=600N
F grav=50N
F grav=800N
F grav=800N
The net force is the sum of all the forces that act on an object.
See examples
F norm= 3N
Net Force examples
Ffrict=5N
F app= 5N
F net = ?
F grav= 3 N
F norm = 3 N
F frict= 5 N
F net = ?
F grav = 3N
Net Force - examples
B
A
50 N
200 N
If F net = 0 N Find the value for A and B