1. Science Investigations

2.  A push or pull on an object  Units: Newton (N) = 1 kg x m/s 2  Net Force (Fnet) : sum of all of the forces that are acting on an object  Balanced Forces: Fnet = 0  Object is at rest or moving with constant velocity  Unbalanced Forces: Fnet is not equal to 0,  Object is accelerating or decelerating

3.  Applied – contact force in the direction the object is moving  Tension- caused by a rope, cable, ect., directed away from the object  Friction- opposes the motion of objects, must have contact  Normal- caused by a surface  Force of gravity- force at a distance, caused by attraction between two objects

4.  Static  Friction of an object at rest  Greater than kinetic friction (harder to get an object moving than to keep it moving)  Friction is greatest when surfaces are rough How can you get a car to move that is stuck in the snow?  Kinetic  Friction of a moving object

5.  Sliding  Two surfaces moving past each other  Rolling  Movement of a circular object on a surface  Fluid Friction  Movement of an object through a liquid or gas  Ex. Air resistance