A rigid body, starting at rest, rotates about a fixed axis with a constant angular acceleration α. Consider a particle a distance r from the axis. Express (a) the radial acceleration and (b) the tangential acceleration of this particle in terms of α, r and time t.(adsbygoogle = window.adsbygoogle || []).push({});

c) if the resultant acceleration of the particle at some instant makes an angle of 57.0 degrees with the tangential acceleration, through what total angle has the body rotated from t=0 to that instant.

i got radial acceleration = rω^2 = (α^2)(t^2)r

tangential acceleration = αr

for c i made a triangle and got cos(57deg) = cos(.99rad) = (α^2)(t^2)r/αr = αt^2

so i plugged it into the kinematics formula

theta = (1/2)αt^2

theta = (1/2)cos(.99rad)

theta = .27 radians

but that is incorrect

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# Homework Help: Rotational Kinematics of a Particle

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