Now that we know what mass is (and what inertia is), we can move forward to Newton's Second Law.
NEWTON'S SECOND LAW OF MOTION: When a net force acts on an object, the object will accelerate in the direction of that force.  The acceleration is directly proportional to the amount of force and inversely proportional to the mass of the object.


Put more quantitatively, F=ma.

This little equation is the cornerstone of classical (also called "Newtonian") physics.  It is very simple and will help us solve many problems.

What are the units involved with the equation F=ma?
 
Term ==> Force mass acceleration
Unit   ==> Newton
The "Newton" is a unit 
that comes from other units.
It is shorthand for: Kg*m/s/s		 Kilogram m/s/s

Since units often confuse people, here is an attempt to straighten folks out...
Read these sentences out loud while you look at the small table above.

  • Mass is measured in Kilograms.  It is a measure of how much stuff is in an object.
  • Acceleration is measured in meters per second per second.  It is the rate of change of speed.
  • Force is mass times acceleration.  Therefore its unit is Kg*m/s/s, also called the Newton.

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