Physical Science Chapter 6 Forces & Motion

Section 1 Gravity and Motion Objs fall to the ground at the same rate because the acceleration due to G is the same for all objs Acceleration depends on both force & mass A heavier obj experiences a greater G force than a lighter obj does  But a heavier obj is also harder to accelerate because it has more mass.  The xtra mass of the heavy obj exactly balances the additional gravitational force.

Acceleration Due to Gravity (G) Acceleration is the rate at which velocity changes over time. The A of an obj is the obj’s change in V divided by the amount of time (T) during which the change occurs All objs accelerate toward earth at a rate of 9.8 meters per second squared

Velocity of Falling Objects V=g x t The change in velocity is the diff between the final velocity and the starting V.

Orbiting Objs Are in Free Fall Weight is a measure of gravitational force The size depends on the mas Free fall—the motion of a body when only the force of gravity (G) is acting on the body: no air resistance

2 Motions Combine to Cause Orbiting An obj is orbiting when it is traveling around another obj in space When a spacecraft is orbiting earth, it is moving forward

Orbiting and Centripetal Force Any obt in circular motion is constantly changing direction An unbalanced force is necessary to change the motion of any obj, there must be an unbalanced force working on any obj in circular motion The unbalanced force that causes objs to move in a circular path called a centripetal force.

Projectile Motion & Gravity PM is the curved path an obj follows when it is thrown or propelled near the surface of the Earth PM has 2 components: horizontal and vertical motion.  They are independenct of each other and have no effect on each other  When they are combined, they form a curved path

Horizontal Motion E.G., throwing a ball There are NO forces to change the ball’s horizontal motion

Vertical Motion G pulls everything on E downward toward the center of E. G pulls a thrown ball downward & gives the ball vertical motion. Acceleration occurs at 9.8 m/s squared