ForceTypes
1
Definition of Force
Drawing the Force
Dimensions and Units of Force
Tension
Elastic Force
Gravity
Normal Force
Friction
Drag
Pulleys
ForceTypes
2
Force
That which causes a particle to accelerate.It is a vector!
Knight’s Definition
A force …
is a push or a pull on an object.It is a vector. It has both magnitude and direction.It requires an agent. Something does the pushing or pulling.It is either a contact force or a long-range force (gravity).
ForceTypes
3
Force, like any vector is drawn as an arrow with the symbol or magnitude and units.
The tail of the force is placed on the part of the object that is experiencing the force.
In a free-body diagram, the tail is placed on the point representing the particle.
The direction of the force and its magnitude are determined by the type of force it is.
ForceTypes
4
Force
The SI unit of force is the Newton (abbreviated as N).
One Newton is the same as one kilogram-meter per second squared.
Another unit of force is the pound.
ForceTypes
5
Tension
The magnitude of the tension is the same everywhere in the rope.
T
T
ForceTypes
6
Name of Force
Symbol
When does this force occur?
Where does this force occur?
Associated Energy
Tension
If an object that is experiencing the force is pulling but not stretching another object
On the object that is experiencing the force at the point where the pulling occurs
No associated energy
T
ForceTypes
7
Spring Force
xk
spF
ForceTypes
8
Name of Force
Symbol
When does this force occur?
Where does this force occur?
Associated Energy
Spring Force
On the object experiencing the force where it connects to the object that stretches/compresses
Elastic Potential Energy
If an object that is experiencing the force is stretching (or compressing) another object
springF
ForceTypes
9
Gravity
GF
GF
r
1m
2m
ForceTypes
10
Name of Force
Symbol
When does this force occur?
Where does this force occur?
Associated Energy
Gravity
or
At the center-of-mass of the object receiving the force
Gravitational Potential Energy
If there are two massive objects present
GF
w
ForceTypes
11
Normal Force
m
N
m
N
w
ForceTypes
12
Name of Force
Symbol
When does this force occur?
Where does this force occur?
Associated Energy
Normal Force
or
If an object touches the surface of another object
On the object receiving the force at the point(s) where it touches the surface
No associated energy
NFn
, N
ForceTypes
13
Friction
m
N
f
Direction of motion
or possible motion m
N
f
Direction of motion
or possible motion
ForceTypes
14
Name of Force
Symbol
When does this force occur?
Where does this force occur?
Associated Energy
Friction
or
If an object touches the surface of another object
On the object receiving the force at the point(s) where it touches the surface
Thermal Energy
sf
kf
ForceTypes
15
Drag
D
ForceTypes
16
Name of Force
Symbol
When does this force occur?
Where does this force occur?
Associated Energy
Drag
If an object is moving through a liquid or gas.
On the object receiving the force at the point(s) where it touches the liquid or gas
Thermal Energy
D
ForceTypes
17
Pulleys
Pulleys simply change the DIRECTION of a force.
T
T