2/16/2012

Post date: Feb 16, 2012 6:5:25 PM

    • Chapter 12 Review

      • Forces

        • A push or a pull

        • An interaction that causes acceleration

        • Measured in Newtons (N)

        • Balanced forces do not cause a change in motion, unbalanced forces do

      • Friction - the force that opposes motion (makes it harder for objects to move, eventually slows them down and stops them)

      • Gravity

        • Acts downward, toward the center of the Earth

        • Falling objects experience gravity downward and air resistance upward (which slows the fall)

        • Falling objects eventually have air resistance and gravity balance out, meaning the object stops accelerating (this is called terminal velocity)

      • Newton's 1st law

        • An object's state of motion will not change unless it is acted on by an unbalanced force

      • Newton's 2nd law

        • Acceleration of an object depends on the force applied to it and the mass of the object

        • Acceleration = Force / mass

      • Weight and Mass

        • weight = mass x acceleration of gravity

        • acceleration of gravity on Earth = 9.8 m/s2

        • acceleration of gravity on moon = 1.6 m/s2

        • Weight depends on the amount of gravity, but weight does not.

      • Newton's 3rd law

        • Whenever an object exerts a force on a second object, the second object exerts and equal and opposite force on the first object

      • Universal forces

        • Electromagnetic force - occurs between charged particles - opposites attract, likes repel

        • Strong nuclear force - occurs over short distances (between protons and neutrons in a nucleus)

        • Weak nuclear force - occurs over short distances (between protons and neutrons in a nucleus)

        • Gravitational force

          • attractive force between all pairs of objects

          • Strength of force depends on the sizes (masses) of the two objects and the distance between them.

    • Review worksheet or page 385-386: pick 15 problems

  • Chapter 12 Test tomorrow