Motion in a Plane

  1. Projectile motion corresponds to ay = - g and generally assumes no air resistance (ax = 0).

    If we choose our coordinate system such that (x(0), y(0)) is the origin, we then have 7 potential unknowns, 4 equations and 35 possible problems for a single projectile.

  2. An object constrained to move in a circular path undergoes centripetal acceleration. Since v is always perpendicular to r (and therefore tangent to the circle):

    and both v and r are constant (assuming uniform circular motion),

    Δv / v = Δr / r.
    Dividing by Δt gives (in the infinitesimal limit)
    acentripetal = v2 / r,
    whose direction is toward the center of the circle.


©2010, Kenneth R. Koehler. All Rights Reserved. This document may be freely reproduced provided that this copyright notice is included.

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