Motion

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Motion
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Definition

• Event that involves a change in the position or
  location of something.

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Motion is Relative

• Relative it is described compared to a
  REFERENCE POINT

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Types of Motion

• Uniform motion - constant speed in a straight
  line
• Accelerated motion motion that is changing in
  speed or direction
• Circular motion - speed is constant but the
  direction of motion is changing continuously

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Scalar Quantities

• Show magnitude amount only
• Speed, time, temperature

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Vector Quantities

• Show magnitude and direction
• Velocity, acceleration, force
• May be graphically represented
• Arrows

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SpeedAverage Speed

• Comparison of time and distance
• A scalar quantity magnitude only
• Distance traveled per unit time
• S d / t
• T d / s
• D s x t

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SpeedInstantaneous Speed

• Speed at any instant

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SpeedConstant Speed

• Speed that does not change
• Instantaneous speed that does not change

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Velocity

• Speed AND direction
• A vector quantity magnitude direction

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Acceleration

• A change in velocity
• Speeding up
• Positive acceleration
• Slowing down
• Negative acceleration
• Deceleration
• Changing direction

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Forces

• Pushes or pulls
• May cause acceleration changes in motion
• May also cause changes in shape

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Balanced Forces

• All forces acting on an object are equal
• There is no motion

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Unbalanced Forces

• All forces acting on an object are not equal
• One or more force is stronger than others
• Motion occurs

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Net Force

• The sum of all forces acting on an object
• A net force of 0
• No motion
• A net force of more than 0
• Motion occurs

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Resultant

• Another term for net force

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Friction

• Force that slows down motion
• Air resistance creates friction in most situations

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Gravity

• Force that attracts all objects toward each other
• More mass more gravity
• Acceleration because of gravity is 9.8 m/s/s
• All objects accelerate at the same rate

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Newton's Laws

• Describe motion and changes in motion

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First Law of Motion

• Law of inertia
• Objects at rest not moving will not begin to
  move until a force acts on them
• Objects in motion will not stop moving until a
  force acts on them
• Objects with more mass have more inertia
• Bigger objects are harder to start and stop

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Second Law of Motion

• Law of acceleration
• A force is needed to change motion
• Objects accelerate in the direction of the force
• The more force applied, then more acceleration
• The more mass an object has, the more force is
  needed to accelerate the object

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Third Law of Motion

• Law of action-reaction
• Forces occur in pairs
• The forces are equal and opposite
• One force is an action force
• The other force is a reaction force
• The forces act on different objects