**P201 Menu**
**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**