Kinematics

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

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

• 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

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

• 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