Astronomy Final

  1. Speed equation
    Speed = Image Upload 2

    Units: (time unit)/(distance unit) - m/s, or mi/hr
  2. Velocity - definition
    The velocity of an object is its speed, together with its associated direction.

    velocity = speed with a direction

    If either the speed of an object changes, or its direction changes, then its velocity changes.
  3. Acceleration
    An acceleration is a change in the velocity (speed &/or direction) of motion in a given amount of time.

    Examples of units: m/sec2, ft/sec2, etc.

    Something at rest is not accelerating and something moving at constant speed in a straight line isn't accelerating.  Must speed up, slow down, or change direction.
  4. Acceleration - equation
    acceleration = (the velocity change)/(the time interval of the change)
  5. Inertia
    A body's ability to resist changes in motion.
  6. Mass (sometimes called inertial mass)
    A measure of that inertia.


    The amount of particles that make up an object.  The more particles it is made from, the greater its mass. (less accurate)

    Units: grams or kilograms
  7. Law of Falling Bodies
    In free-fall, all objects accelerate downward with the same acceleration.
  8. Force
    A push or pull on an object.
  9. Angular momentum
    The momentum involved when objects are spinning or circling (orbiting)
  10. Torque
    Anything that can cause a change in an object's angular momentum (twisting force)
  11. Kepler's - Law of the Conservation of Angular Momentum
    Example: ice skater spinning around and getting faster when she pulls her arms in.

    Reduces the distance between arms and the axis of rotation - increases the rotation speed.

    When a planet gets closer tothe sun, decreasing the distance around which it travels, its speed increases.
  12. Universal Law of Gravitation
    The larger either of the two masses are, the stronger the force of gravity between them.  However, the farther apart they are, the bigger d (distance) is and the weaker the gravitation force.

    The d changes by d2 - the gravitational attraction decreases/increases by a factor of 3 x 3 = 9, not 3 + 3 = 6
  13. Weight
    The force of gravity felt by that object but the mass of an object is the amount of matter the object has.
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Astronomy Final
Astronomy stuff