Physics Test 1

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Physics Test 1
2012-02-06 19:15:29
Physics one physical science

Physical Science
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  1. Polaris
    • North Star
    • Does not move
    • Polaris is on the same axis as the earth
  2. Retrograde Motion
    • The apparent backward motion of objects in the sky
    • Caused by the earth moving faster than other objects further away from the sun
  3. Geocentrism
    • Idea that the Earth is the center of the solar system
    • Ptolemy's Idea, Ptolematic system
    • Orbital patterns thought to be circular
  4. Heliocentrism
    • Idea that planets revolve around the sun
    • Copernicus' Idea, Copernican system
    • Orbital Patterns still thought to be circular
  5. Tycho Brahe
    • Made incredible observations with crude instruments
    • Had most advanced instruments of the time
  6. Kepler's Laws
    • Three Laws
    • 1. Paths of planets around the sun are ELIPSES with the sun as focus. (Planetary motion, Eliptical Foci)
    • 2. Planet moves slower when further away from the sun, sweeping equal amounts of area in the same amount of time.
    • 3. Time taken for 1 orbit is related to distance from the sun
  7. Gravity
    • Newton's Law
    • The FUNDAMENTAL FORCE that explains all motion that can be observed in the universe

    Acceleration due to gravity (on earth) is only in an up/down direction
  8. Gravitational Constant (G)
  9. Tides
    Gravity attractions between the sun and moon
  10. Spring Tides
    • Larger
    • At new moon and full phase
    • The sun and moon's gravity pull in the same direction
  11. Neap Tides
    • Weaker
    • Angle of gravitational pull of moon and sun is a right angle
    • 1st and 3rd quarter phases
  12. Unit system used in the United States
    British Imperial
  13. International System of Units
    • Systeme Internationale
    • S.I./ Metric System
    • Ex. Meters kilograms
  14. Motion
    • A change in position
    • Everything in the universe is in constant motion
  15. Speed
    • How fast the location of any object is changing
    • Rate of change of position
    • Instantaneous Speed: speed traveling at during one moment of time. (Ex. Spedometer in car)
    • Scalar quantity
  16. Scalar Quantity
    • A quantity at wich only magnitude is specified
    • Time, mass, speed, temperature
  17. Vector Quantity
    • A quantity in which both magnitude and direction is specified
    • Velocity, Acceleration, Weight (Gravity too)
  18. Math with Vectors
    • Represented by an arrow
    • Length of arrow = magnitude of vector
    • Arrow head points in the direction of the vector
  19. Velocity with Vectors
    Have direction: North, east, 45 degrees
  20. Acceleration
    • Rate of change of velocity
    • Acceleration is negative if it is opposite to the motion of the object
  21. Changes In Velocity
    • If it increases in magnitude (5 m/s -> 15 m/s)
    • Decreases in magnitude
    • Changes direction
  22. Galileo's Experiments
    • Velocity of a falling object is proportional to the length of time that the object has been falling
    • In the abscence of air, all things fall the same rate
  23. Newton (Person)
    • Wanted to know why things move
    • Developed the idea of FORCE
  24. Force
    • A pull or push constitutes a force
    • Units: Newton (N) or Pound (lb)
    • Vector Quantity
    • At any time, there may be several forces acting on an object: Net Force
  25. Weight
    Force due to gravity
  26. Uniform motion
    • Object moves with constant velocity
    • Net Force = 0
  27. Accelerated motion
    • Velocity isn't constant... object accelerates
    • Net force does not equal 0
  28. Inertia
    • Object's resistance to change and motion
    • Greater mass = greater inertia
  29. Newton's Laws
    • 1. Law of Inertia: if Fnet= 0, a body at rest will stay at rest
    • 2. If there is a net force, the object accelerates
    • 3. Action-reaction: For every action, there is equal opposite reaction. Forces come in pairs.
  30. Friction
    • Static Friction: Non-moving
    • Kinetic friction-moving
    • In order to get an object moving we must overcome static friction
    • Rougher materials have greater frictional forces
    • Frictional forces always oppose the motion of the object
  31. Air Resistance
    • Friction during free fall means net force is reduced
    • As velocity increases, so does frictional force
    • Frictional force= weight force, net force=0
  32. Terminal Velocity
    An object in freefall will fall at a constant velocity when air resistance is involved
  33. Centripetal force
    • "Center seeking" force
    • The direction is always toward the center of any curved pattern
    • Changing in direction... accelerate.
    • In circular motion, there is always a different velocity (vector, changing direction), but the speed (scalar) remains constant
  34. Law of Gravity
    • The gravitational force of attraction between two objects
  35. Work
    • Done whenever a force causes a motion or a change in motion
    • Scalar quantity
    • W= fd (F=ma)
    • Work against Gravity: Wg=mgh
    • Something has to move
    • Force must be the force along the direction of motion
    • Unit: Nm or Joule
  36. Energy
    • The ability to do Work
    • Work done = energy used
  37. Power
    • The rate at which work is done
    • Unit: J/S or 1 Watt
    • Watts over time
  38. Kinetic energy
    • Energy an object has due to motion
    • No velocity, no KE
    • Larger mass or velocity, larger KE
    • Double Velocity, KE increases 4x

  39. Potential Energy
    • Gravitational Energy/ Gravitational Potential Energy
    • Energy an object has due to its position above the ground
    • GPE= mgh
  40. Magnetic Potential Energy
    Due to object's position in a magnetic feild
  41. Conservation of Energy
    May change from one form to another, but the total amount of energy in the universe is constant

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