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Class_Notes

Newton's Laws

1. Law of Inertia A body naturally moves in a straight line 
at constant speed natural means no external influence on body
or:

Sum Forces ON body = 0

2. Law of Non-Inertia. The net force ON a body causes an acceleration
in direction of net force and of magnitude given by

Sum of Forces ON body equals mass x acceleration.

3. Law of Action - Reaction.  ALL Forces are interactions 
between two bodies (A & B) If body A exerts force on body 
B (FAB), then body B exerts a force on body A (FBA) which 
is equal and opposite. FBA = - FAB

Other examples:

Conical Pendulum

Newton's Law for rotation

Whirlygig
Toronado Bottle

Now on to Horse and Wagon

Apply 2nd Law to Wagon (4 wheels)

Path: FHW - 4 fSW = Mw apath
Perp: 4 FSW - FEW = Mw aperp

Apply 2nd Law to Horse (4 feet)

Path: 4 fSH - FWH = Mh apath
Perp: 4 FSH - FEH = Mh aperp

Other applications

Car Moving to Right

Car Coming At You and curving to right (your left)

Level Road ..................Banked Road

Now a little quiz about Newton's Laws

Concept of Collisions.......Explosions.

Application of Newton's 2nd and 3rd Laws.

F = m a  or  F = D(mv)/Dt

Or  F Dt = D(mv)

Where D = delta (change)

 mv = momentum

so force equals the rate of change of momentum of a body OR
Force acting for a time (Dt) causes a change in momentum.

For example, billiards

A: Head On Collision

B. Glancing Blow

Other examples:

Shooting guns

Shooting rockets

Interactive Physics