Lesson 3 - Introduction to Classical Mechanics - Moving On Up

Now that you know about the Force lets quickly review the formulas and definitions we have learned before moving onto Newton's Laws of Motion!

• Matter: Anything that has Mass and Volume
  
• Volume: The amount of three-dimensional space a substance (solid, liquid, gas, or plasma) or shape occupies or contains. Volume is used to determine the Density of an object.
  
• Mass: Mass is the amount of material or matter an object is made up of. Ability to resist motion when acted on by a Force due to the quantity of material in the object. Represented by (m) and the unit of measurement is the Gram (g)
  
• Density: Tells us how tightly crammed together matter is. density = mass / volume
  
• Force: Any type of influence that causes a free body to undergo an acceleration
  
• Displacement: The shortest path between two points and thus is always less than or equal to distance. Work = Force * Displacement
  
• Speed: The rate (distance & time) at which an object moves relative to some defined reference point of view. speed = distance / time
  
• Velocity: Velocity = Displacement / Time
  
• Acceleration: The rate at which an object changes its velocity. Acceleration = ∆ Velocity / Time
  

 

Newton's Laws of Motion

 

In Physics, like all other subjects there have been some truly great men and women. Sir Isaac Newton is one member of this group in the world of Physics.

Newton came up with three laws which apply to the motion of objects in classical physics. It is important to note that these laws do not apply when speeds approach the speed of light or where extreme gravitational fields exist (like in a black hole).

First Law

• Unless acted on by an outside force, an object is at rest and stays at rest.
  
• Unless acted on by an outside force, an object moving with uniform velocity continues to move at that velocity
  

Second Law

If an object of mass m (kilograms) is acted on by a force of magnitude F (newtons), then the magnitude of acceleration a (meters per second squared) can be found by:

• a = F / m
  
• F = ma
  

Third Law

Every action is attended by an equal an opposite reaction.

If Object A exerts a Force F on Object B then Object B exerts a Force F on Object A.