ENSC2004 - Lecture 13

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ENSC2004 - Lecture 12
Newton’s Laws - Slides

Newton’s Laws of Motion

• In dynamics, we commonly use Newton’s 2nd law:
  $F=ma$

Mass and Weight

• Mass is an absolute property of a body
  • Independent of gravitational field
• Weight is not absolute
  • Dependent of gravitational field:
    $W=mg$

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Equations of Motion: Rectangular Coordinates - Slides

Friction

• Friction acts in opposite direction of applied force
  • Questions will indicate whether you need to consider friction
    e.g. smooth surface, rollers present → no friction

Static Coefficient of Friction: ${\mu }_s$ → $F_s={\mu }_{s}N$
Kinetic Coefficient of Friction: ${\mu }_k$ → $F_k={\mu }_{k}N$

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Equations of Motion: Normal & Tangential Coordinates - Slides

Normal and Tangential Coordinates

• When particle moves along a curved path, may be more convenient to to use normal and tangential coordinates
  • See Normal and Tangential Components
    $a_n=\frac{v^2}{\rho }$

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ENSC2004 - Lecture 14