Physical Science-Chapter 11 

Kinematics

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11A Describing Position

• Wandering Planets
  • %%Mechanics%%: the study of motion
  • %%Kinematics%%: the study of how things move
  • %%Dynamics%%: the branch of physics that studies forces and how they can change an object’s motion
• History of Mechanics
  • %%Retrograde Motion%%: the apparent motion of some planets in which they appear to slow down, stop, reverse their direction, and then resume their normal motion
  • %%Quantum Mechanics%%: the branch of physics that explores the behavior of matter and energy at the atomic and subatomic level
  • %%Relativistic Mechanics%%: the study of the motion of objects whose speeds are near the speed of light
• Frame of Reference
  • %%Frame of reference%%: a coordinate system used to describe the motion of an object
• Distance and Displacement
  • %%Distance%%: how far an object moves during a time interval
  • %%Displacement%%: a vector quantity that describes a change in position
• Scalars and Vectors
  • %%Scalar%%: a measurable quantity that consists of magnitude (size) only
  • %%Vector%%: a measurable quantity with both magnitude and direction

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11B Describing Motion

• %%Speed%%: a scalar quantity indicating the rate at which an object moves
• %%Velocity%%: a vector quantity indicating the rate at which an object’s position changes

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• Momentum
  • %%Momentum%%: a property of a moving system that is equal to its velocity times its mass
  • %%Conservation of Momentum%%: states that within a closed system - a system that is isolated from outside. pushes or pulls - the total momentum remains constant

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11C Changing Motion

• %%Acceleration%%: the rate of change in velocity
• %%Free Fall%%: the motion of an object that falls due to gravity alone, with no other forces acting on it

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• Two-Dimensional Motion
  • %%Circular Motion%%: movement along a circular path
  • %%Centripetal Acceleration%%: acceleration that causes an object to move along along a circular path
  • %%Projectile Motion%%: the two-dimensional motion of any flying object whose path is determined by the influence of an external force only, such as gravity
  • %%Trajectory%%: the curved path of a projectile

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