Chapter 1 Forces and Pressure

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Chapter 1Forces and Pressure

• Section 1-1
• Forces and Motion

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I. Velocity, Acceleration, and Motion

• Velocity
• How fast an object is going in a given direction
• Ex 30 miles per hour, east
• Acceleration
• The change in either the speed of an object or
  its direction

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• Inertia
• The tendency to resist changes in motion
• Mass size inertia
• The larger the mass, the greater the inertia.
• Harder to move
• Ex semi-truck

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• The smaller the mass, the less the inertia
• Easier to move
• Ex. Garbage can

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II. Newtons First Law

• An object in motion remains in motion, an object
  at rest remains at rest, unless acted on by an
  outside force.
• Force a push or pull
• Something must push on you to make you move

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III. Friction

• A force that resists motion between two objects
  in contact
• Friction is necessary when we want acceleration
• Friction slows things down when we want to
  accelerate.

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• Without friction we would not be able to move
• Without friction we would not be able to stop.

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IV. Gravity

• Not something we usually think about.
• Due to gravitational force, all free falling
  objects accelerate downward about 9.8 meters per
  second per second (m/s2).

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• All objects fall at the same rate unless air
  resistance causes objects to slow down

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• As objects fall, more massive objects are more
  strongly attracted to the earth you would think
  they would fall faster. They are also harder to
  accelerate their inertia reduces their
  acceleration exactly as much as greater
  attraction increases it.