DYNAMICS
III. Definition - study of relationship between force & motion
A) 3 Laws of Motion
1st Law - Law of Inertia
Object at rest
tends to stay at rest.
Object in motion
tends to stay in motion
in straight line
Why is it initially so difficult to pedal a bike
when you start from rest.
Why is it so easy to pedal the bike once you obtain your desired speed
Inertia - Object at rest tends to stay at rest (force required to change motion)
Object in motion tends to stay in motion (force only needed to offset friction)
..... unless acted on by an unbalanced force.
|
Balanced Forces
Unbalanced Forces
|
In other words ...
If a moving object has
no unbalanced force on it,
it would maintain its
speed and direction forever!
Unbalanced Forces
Change Motion
Speed
and/or
Direction
Moon has Unbalanced Force On It!
 Unbalanced ForcesAnimation |
Larger the mass,
the greater the inertia
|
|
 |
Inertia and Mass Directly Related
Twice the mass
Twice the Inertia
Why are the most massive (most inertia)
football
players lineman?
Why are the least massive (least inertia)
football
players receivers?
Receivers want to change motion,
lineman want to hold
their ground
What makes the world go 'round?
Nothing!
An Object in Motion Tends to Stay in Motion
|
|
Dynamic Equilibrium Animation |
|
|
First Law Game
Animation |
Eggs and Inertia - Physics.org