Transcript Types of Forces (print version)

Types of Forces
Force – An interaction between two
objects resulting in a push or a
pull
Types of Forces
Example 1
Consider the water bottle below at
rest on a table.
System Schema – a visual representation
of the objects that are interacting
and the types of interactions
(Forces) that are occurring.

Force of GravtityFg  = A long range
force exerted by the Earth
on an object
Water
Bottle

Fg
Earth
Types of Forces
Example 1
Consider the water bottle below at
rest on a table.

Normal Force FN  = A support force
that always acts perpendicular
(Normal) to the surface

FN

FN
Table

Fg
Water
Bottle

Fg
Earth
Floor
Types of Forces
Example 1
Consider the water bottle below at
rest on a table.
The water bottle has two interactions
leading to two forces acting upon it.

FN
Table
Water
Bottle

Fg
Earth
Types of Forces
Example 2
Consider the water bottle below
pulled horizontally across the floor
at constant velocity.
Types of Forces
Example 2
Consider the water bottle below
pulled horizontally across the floor
at constant velocity.

FN
Floor

Ff
Water
Bottle

Fg
Earth

Force of Friction F   Force that opposes the motion or attempted motion of
f
one surface over another. Always acts parallel to the
surfaces involved.
Types of Forces
Example 2
Consider the water bottle below
pulled horizontally across the floor
at constant velocity.

FN
Floor

F ffk
Water
Bottle

Fg
Types of friction:
Earth

Force of Kinetic Friction F fk  = force of friction due to surfaces in relative motion

Force of Static Friction F fs = force of friction that opposes attempted motion
of the surfaces
Types of Forces
Example 2
Consider the water bottle below
pulled horizontally across the floor
at constant velocity.

FN
Floor

F fk
Water
Bottle

Applied Force FA  = the force which is
applied to an object by a
person or another object.

FA

Fg
Me
Earth
Types of Forces
Example 2
Consider the water bottle below
pulled horizontally across the floor
at constant velocity.

FN
Floor

F fk
Water
Bottle
The water bottle has four interactions
leading to four forces acting upon it.

FA

Fg
Me
Earth
Types of Forces
Example 2a
What would change about the system
schema if the bottle was pulled across the
floor at constant velocity by a rope?
Types of Forces
Example 2a
What would change about the system
schema if the bottle was pulled across the
floor at constant velocity by a rope?

FN
Floor

F fk
Water
Bottle

Force of Tension FT  = force which is transmitted
through a string, rope, wire or cable
when it is pulled tight by forces acting
from each end.

FT

Fg
Rope
Earth
Types of Forces
Example 2a
What would change about the system
schema if the bottle was pulled across the
floor at constant velocity by a rope?

FN
Floor

F fk
Water
Bottle
The water bottle has four interactions
leading to four forces acting upon it.

FT

Fg
I interact with the rope, not
the water bottle.
Me

FA
Rope
Earth
Types of Forces
Example 2a
What would change about the system
schema if the bottle was pulled across the
floor at constant velocity by a rope?

FN
Floor

F fk
Water
Bottle
The water bottle has four interactions
leading to four forces acting upon it.

FT

Fg
Rope
Earth