1.  Bell Ringer: What do you think causes an object to start moving, stop moving, or change direction? What do you think causes an object to start moving, stop moving, or change direction?

2. Section 10.1 Objectives  Today we will learn: What a force is. What a force is. How balanced and unbalanced forces are related to an object’s motion. How balanced and unbalanced forces are related to an object’s motion.

3. 10.1 The Nature of Forces  FORCE A push or a pull A push or a pull Causes an object to start moving, stop moving, or change direction Causes an object to start moving, stop moving, or change direction When one object pushes or pulls another object, we say the first object exerts a FORCE on the second object When one object pushes or pulls another object, we say the first object exerts a FORCE on the second object

4. 10.1 The Nature of Forces  FORCE Described by strength and direction Described by strength and direction Strength is measured in NEWTONS (N) Strength is measured in NEWTONS (N) Represented with an arrow (  or  ) Represented with an arrow (  or  ) Arrow points in direction of the force Arrow points in direction of the force

5. 10.1 The Nature of Force  Often, more than one force acts on an object at one time… Combination of all forces = NET FORCE Combination of all forces = NET FORCE Net force determines whether an object moves and in which direction it moves Net force determines whether an object moves and in which direction it moves Forces in SAME direction, add together Forces in SAME direction, add together Forces in OPPOSITE directions, subtracted Forces in OPPOSITE directions, subtracted Same strength in opposite direction, canceled Same strength in opposite direction, canceled

6. 10.1 The Nature of Force  Net force on an object means forces are UNBALANCED  Unbalanced forces are what cause objects to start or stop moving or change direction

9. 10.1 The Nature of Force  Equal forces acting in opposite directions on an object are BALANCED FORCES  Balanced forces acting on an object do not change the object’s motion…  Because when equal forces are exerted in opposite directions, the net force is ZERO

12. Our objectives  Did we learn?? What a force is. What a force is. How balanced and unbalanced forces are related to an object’s motion. How balanced and unbalanced forces are related to an object’s motion.