1. More About Force 3) When one object exerts a force on a second object, the second exerts an equal and opposite force on the first. F AB = -F BA

2. Weight The magnitude of the force of gravity. w=F g =mg (Weight is not mass!) g= 9.80 m/s 2

3. Normal Force -A reaction force (reacting to another force) that is perpendicular (normal) to a surface. n w

4. Free Body Diagram

6. ex: A 3.0 kg mass is on a horizontal, frictionless table, and is attached to a string. The string runs over a light pulley, and is attached to a 1.5 kg mass. Find the tension in the string and the acceleration of the masses. m 1 =3.0kg m 2 =1.5kg