3. Net force (Combining force); It is the total amount of Force, ( minus the forces that cancel each other out ). Force of gravity Force of muscles Net force
4. Balanced Forces Unbalanced Forces When the net force is Zero. -> NO movement When the net force is NOT Zero. -> movement
17. Gravity and Motion Free Fall Free fall- when gravity is the only force acting on an object (free fall acceleration is directed toward center of earth) The acceleration of gravity ( g ) for objects in free fall at the earth's surface is 9.8 m/s 2 . Galileo found that all things fall at the same rate in the absence of air resistance, regardless of their mass
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19. Projectile Motion When an object is thrown into the air, two forces and two motions affect the movement of the object. The object may be thrown horizontally with a certain force, but the vertical force of gravity combines to affect the motion. Slow projectile - shoot a monkey Fast projectile - shoot a monkey