Section 2.1 Forces change motion Mrs. Leos Eighth Grade Science
Forces A push or a pull Three types Contact Force Gravity Friction When objects use force by pushing or pulling an object. Gravity Friction
Vectors A quantity that measures both size and direction Force is a vector Direction of arrow is direction of force Size of arrow is size of force (bigger arrow = more force, smaller arrow = less force) What other kind of vector have you already learned about?
Net Force Overall force acting on an object when all the forces are combined. Total force that affects an object when multiple forces are combined. The net force depends on both the direction and the size of individual forces.
Unbalanced Forces Balanced Forces Object does not move No net force Same effect as no force Also act on object moving in straight line with constant velocity Object moves Net force in one direction One force on an object is greater than another
Measuring Net Force Identify forces to combine. Put tail of second force arrow to tip of first. Maintain size and direction Measure from tail of first arrow to tip of second force arrow.
Combining forces in opposite directions
Combining forces in the same direction
Newton’s First Law Objects at rest remain at rest, and objects in motion remain in motion with the same velocity, unless acted upon by an unbalanced force Objects with no net force acting on them have either constant velocity or zero velocity Force is needed to start, change, or stop motion
Inertia Resistance of an object to a change in motion Directly related to an object’s mass