PHY 102: Chm 102, Bio 102

Principle: The Beer-Lambert Law states that the absorbance of a solution is directly proportional to its concentration and the path length of the light through the solution. $A = \epsilon bc$, where A is absorbance (unitless), $\epsilon$ is the molar absorptivity (L mol$^{-1}$ cm$^{-1}$), b is the path length (cm), and c is the concentration (mol/L). This method is widely used in chemistry and biochemistry for quantitative analysis.

• Newton's First Law (Law of Inertia): An object at rest stays at rest, and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an external unbalanced force.
  • Mathematically: If $\vec{F}_{net} = 0$, then $\vec{a} = 0$.
• Newton's Second Law: The acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass. The direction of the acceleration is in the direction of the net force.
  • $\vec{F}_{net} = m\vec{a}$
  • Component form: $\sum F_x = ma_x$, $\sum F_y = ma_y$, $\sum F_z = ma_z$.
• Newton's Third Law: For every action, there is an equal and opposite reaction. If object A exerts a force $\vec{F}_{AB}$ on object B, then object B simultaneously exerts a force $\vec{F}_{BA}$ on object A, such that $\vec{F}_{AB} = -\vec{F}_{BA}$. These forces act on different objects.