Phys 3, Section 2 				September 4, 1996 

RELATIVE MOTION

Reference Frames

• Inertial Frames: constant velocity system
• Coordinate Systems
• Relative velocities: s_AC = s_AB + s_BC
  

Vector Components

• Choose orthogonal coordinates
• Break original vector into components along coordinates
• A = A_x i+ A_y j
• Sum of vectors is sum of their components:
• A + B = (A_x + B_x) i + (A_y + B_y) j
  

Pythagorean theorem:

• C² = A² + B² (right triangle only)

Right Triangle:

• Sin = opposite/hypotenuse
• Cos = adjacent/hypotenuse
• Tan = opposite/adjacent
  

Law of Sines:

• a/b = sinA / sinB

Law of Cosines:

• c² = a² + b² - 2ab cosC