Chapter 8 Notes

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Chapter 8 Notes

• Motion and Forces

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Chapter 8.1 Notes

• Speed distance traveled divided by the time
  interval during which the motion occurred
• SpeedDistance/time
• Constant speed speed does not change

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• Velocity is a quantity describing both speed and
  direction (same number as speed but with a
  direction added)
• Momentum a quantity defined as the product of an
  objects mass and its velocity
• Momentum Mass x Velocity

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Chapter 8.2 Notes

• Acceleration change in velocity, if the object
  speeds up, slows down, changes direction.
• Acceleration

Final velocity - initial velocity
time
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• Force the cause of acceleration, or change in an
  objects velocity.
• Balanced forces are forces acting on an object
  that combine to produce a net force equal to
  ZERO.
• Unbalanced forces are forces acting on an object
  that combine to produce a net nonzero force.

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• Friction the force between two objects that
  opposes the motion of either object. So whenever
  two objects touch there is friction.
• Air resistance is a type of friction.
• Low friction shoes on ICE
• High friction shoes on pavement

7

• Gravity- the attraction between two particles of
  matter due to their mass.
• The larger the mass the larger the gravitational
  pull.
• The closer together the two objects are the
  greater the gravitational pull.

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Chapter 8.3 Notes

• Newtons 3 Laws of Motion
• An object at rest remains at rest and an object
  in motion maintains its velocity unless it
  experiences an unbalanced force.
• The unbalanced force action on an object equals
  the objects mass times its acceleration. Force
  (m)(a)
• For every action force, there is an equal and
  opposite reaction force.

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Newtons 1st law

• Inertia the tendency of an object to remain at
  rest or in motion with a constant velocity.
• That is why we wear seatbelts, put babies in car
  seats, need to sit away from airbags.
• New York State passed the first seat belt law in
  the US in 1984 under the leadership of John D.
  States, an orthopedic surgeon who dedicated his
  career to improving automotive safety.

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• Remember, it is not just the law, but a way to
  help prevent accidental injury or death when your
  children are riding in a vehicle.  These laws are
  the minimum requirements.  Children are safer
  riding in booster seats through  80 pounds than
  using the vehicle's seats and restraint systems
  designed for adults.       Many states are
  seeking to change their laws to require children
  stay in restraints through 8 years and 80
  pounds. 

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Newtons 2nd law

• Free fall is when the force of gravity is the
  only force action on an object.
• Gravity (g) 9.8 m/s2
• Weight mass times gravity
• Terminal velocity is the maximum velocity reached
  by a falling object.

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• Weight is the pull of gravity on an
  objectchanges from place to place.
• Mass is the amount of matter in an objectNEVER
  changes.

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How Fast do Rockets Go??
Flight Plan Speed Required
Earth to LEO (low Earth orbit) 17,000 mph
Earth to Earth escape 24,200 mph
Earth to lunar orbit 25,700 mph
Earth to GEO (geosynchronous Earth orbit) 26,400 mph
Earth to solar escape 36,500 mph
Rockets deal with Newtons 3rd law of motion
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Work Cited

• Sonic Boom Plane. April 7, 2008.
  http//www.aviationexplorer.com/sonicboomplane_nav
  y.jpg
• US map of car seat law and info. April 9, 2008.
  http//www.inventiveparent.com/state-laws.htm
• Seat belt laws. April 9, 2008.
  http//en.wikipedia.org/wiki/Seat_belt_legislation
  
• rocket info. April 9, 2008. http//www.qrg.north
  western.edu/projects/vss/docs/Propulsion/2-how-fas
  t-conventional.html