Friction in Motion Gravity and Motion

Terms Terminal velocity~ the constant velocity of a falling object when the size of the upward force of air resistance matches the size of the downward force of gravity Free fall~ the condition and object is in when gravity is the only force acting on it Projectile motion~ the curved path an object follows when thrown or propelled near the surface of the Earth

All Objects Fall with the Same Acceleration Acceleration due to gravity Fall at same rate because acceleration due to gravity is the same for all objects Force of gravity larger between Earth and a larger object than Earth and a small object Difference in force canceled by difference in mass Accelerating at a constant rate Objects accelerate toward Earth at a rate of 9.8 m/s2

All Objects Fall with the Same Acceleration

Air Resistance Slows Down Acceleration Air Resistance affects some objects more than others Depends on size and shape of object Acceleration stops at the terminal velocity Upward force from air resistance continues to increase until it exactly matches the downward force of gravity Object falls at constant velocity Free fall occurs when there is no air resistance

Orbiting Objects Are in Free Fall Two motion combine to cause orbiting Forward motion & free fall Figure 7 page 142 (may want to sketch) The role of gravity in orbiting Centripetal force is the unbalanced force which causes objects to move in a circular pattern Gravity provides centripetal force

Projectile Motion and Gravity Horizontal Motion Object moves parallel to the floor After the ball leaves the pitcher’s hand, its horizontal velocity is constant. The ball’s vertical velocity increases because gravity causes it to accelerate downward. The two motions combine to form a curved path.

Projectile Motion and Gravity Vertical Motion Gravity pulls object making object move perpendicular to the floor Figure 10 page 144 (may want to sketch tonight)