Inertial Frame, Euler’s First Law Skip to Euler’s Second Law

Key Concept: Euler’s first law requires that the sum of the external forces on a system of particles (or rigid body) equals the sum of the ma’s of the particles of the system referred to the inertial frame.

In a Nut Shell: Motion of a particle (or the center of mass of a rigid body) depends on its

frame of reference. A special frame of reference is the so-called “inertial frame of reference”.

In most cases a frame of reference attached to the earth is sufficient. Euler’s first and second

laws hold for inertial frames of reference.

Consider a rigid body of mass, m, located at its center of mass, C. Then the expression for Euler’s first law is

Σ F = m a_C

Euler’s First Law

NOTE: Euler’s first law is a vector equation. In a plane it can have rectangular, polar, or

intrinsic (normal-tangential) components.

where Σ F is the sum of all external forces acting on the particles (rigid body); note

a particle can be thought of as a body whose entire mass is concentrated at a point

m is the mass of the particle (or entire body)

a_C is the acceleration of the particle or center of mass of the rigid body in the inertial frame

of reference

Click here to continue with discussion of Euler’s first Law. Click here for a discussion of strategy.

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