2.  F = ma  m is measured in kg  a is measured in m/s 2  F is measured in kg m/s 2, called a Newton (N)

3.  Acts at a distance (gravitational field)  Force due to Gravity = Weight  Acceleration due to Gravity = Constant  g = 9.8 m/s 2

4.  Contact Force  Acts perpendicular to the surface

5.  Contact force  Acts parallel to the surface  Acts opposite the direction of motion

6.  Contact force  Acts opposite the direction the spring is stretched or compressed  Proportional to stiffness of spring and how much it is stretched or compressed

7.  Contact force  Force exerted by a string or rope  Always acts along the string or rope  Equal on both ends of the string or rope* * Unless you have a pulley with mass, like in AP Physics