Forces and Free-Body Diagrams PDF

PHYSICS Newton’s Laws of Motion Forces and Free-Body Diagrams  Force Action (push or pull) that changes an object’s state of motion ⚪ Slow down ⚪ Speed up acceleration ⚪ Change direction  Force - units Like we discussed last week, we measu...

PHYSICS Newton’s Laws of Motion Forces and Free-Body Diagrams  Force Action (push or pull) that changes an object’s state of motion ⚪ Slow down ⚪ Speed up acceleration ⚪ Change direction  Force - units Like we discussed last week, we measure a force in Newtons (N) Let’s discuss… How do forces affect the motion of an object?  Balanced vs Unbalanced FN A. Net force - sum of the forces Left is negative Down is negative Fg B. Balanced forces = NO motion; Net force = 0 Newtons C. Unbalanced forces = change in motion Will move in direction of greatest force  Free Body Diagram Shows all forces (vector) acting on an object Unit for force = N (Newton) FN = 500 N Ff = - 200 N Fp = 1000 N Fg = - 500 N  Common Forces Fg = weight 🡪 downward FN = normal 🡪 perpendicular to surface Ff = friction (includes air) 🡪 opposite to motion Fp = push/pull FT = tension in string FN FRICTION FRICTION Fg  Net Force The overall force acting on an object after all the forces are combined. In other words, vector sum of all forces on an object Forces in the same direction add together. Forces in opposite directions subtract from one another. Net Force (continued) Let’s discuss… In what direction does Earth’s gravity act? Earth’s gravity acts downward toward the center of Earth. Let’s discuss… How do gravity and air resistance affect a falling object? Gravity causes objects to accelerate downward, whereas air resistance acts in the direction opposite to the motion and reduces acceleration.  Free body diagram: A book lying on A wrecking ball hanging A helicopter a level table vertically from a hovering in cable place Which way is the object moving?