Linear Speed and Angular Speed!!! Please help, I don't understand the problem.
*A wheel of radius 30 cm revolves at a rate of 10 revolutions per second. A dot is painted at a point P on the rim of the wheel.
a.) Find dx/dt as a function of theta
b.) When is the absolute value of the rate of change of x the greatest? Least?

Question

Linear Speed and Angular Speed!!! Please help, I don't understand the problem.
*A wheel of radius 30 cm revolves at a rate of 10 revolutions per second. A dot is painted at a point P on the rim of the wheel. 
a.) Find dx/dt as a function of theta 
b.) When is the absolute value of the rate of change of x the greatest? Least?

phi · Answer

how about using
$$ x = r \ \cos \theta$$
with r= 30 
take the derivative with respect to time "t" of both sides.

anonymous · Answer

how does it become x=r cosθ ?

phi · Answer

If the wheel is fixed, and spinning, and we measure the angle from the positive x-axis, then by geometry,  x (horizontal distance from the center) is r cos theta
or is this wheel moving along a road ?

phi · Answer

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