Changes

<math>\Sigma \vec F = m \vec a</math> where

<math>\Sigma \vec F = m \vec a</math> where

* <math>\Sigma \vec F</math> = total force acting on the object

* <math>\Sigma \vec F</math> is the net [[force]] acting on the object

* m = mass of the object

* <math>m</math> is the mass of the object

* <math>\vec a</math> = acceleration of the object

* <math>\vec a</math> is the acceleration of the object

This law also applies to a system of objects.  

This law also applies to a system of objects.  

Newton originally wrote this as  

Newton originally wrote this as  

:<math>\Sigma \vec F = \frac{d \vec p}{dt}</math>

:<math>\Sigma \vec F = \frac{d \vec p}{dt}</math>

where <math>\vec p</math> is the [[momentum]] of the object.  Momentum is defined as mass times velocity, p = m*v. This formulation is more general.  It reduces to F = m*a when the object has a constant mass.

where <math>\vec p</math> is the [[momentum]] of the object.  Momentum is defined as mass times velocity, <math> \vec p = m \vec{v}</math> This formulation is more general.  It reduces to <math>\vec F = m \vec{a}</math> when the object has a constant mass.

'''3.  For every action, there is an equal and opposite reaction.'''

'''3.  For every action, there is an equal and opposite reaction.'''

If object A exerts a force on object B, object B will exert a force equal in magnitude and opposite in direction on object A.  For example, ff the earth pulls you down with a force of 1500 Newtons, you pull up on the earth with a force of 1500 Newtons.  (Of course, since F=ma, and the earth's mass is much greater than yours, the earth accelerates much less than you do.)

If object A exerts a force on object B, object B will exert a force equal in magnitude and opposite in direction on object A.  For example, if the earth pulls you down with a force of 1500 Newtons, you pull up on the earth with a force of 1500 Newtons.  (Of course, since <math>\vec F = m \vec{a}</math>, and the earth's mass is much greater than yours, the earth accelerates much less than you do.)

 

== Angular Kinematics ==

== Angular Kinematics ==

These same basic laws are true with respect to angular motion, that is, for a particle moving in a circle.  In this case, the position is described by an angle, and is measured in [[radian]]s.  Its first derivative, ω (measured in radians/second), is called angular velocity; its second derivative α is called angular acceleration.  The kinematic equations of rotational motion are analogous to those of linear motion:

These same basic laws are true with respect to angular motion, that is, for a particle moving in a circle.  In this case, the position is described by an angle, and is measured in [[radian]]s.  Its first derivative, ω (measured in radians/second), is called angular velocity; its second derivative α is called angular acceleration.  The kinematic equations of rotational motion are analogous to those of linear motion: