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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
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Physical ScienceChapter 6 Forces & Motion
Section 1Gravity 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