Current Attempt in Progress

A rider on a mountain bike is traveling to the left in the figure. Each wheel has an angular velocity of $+21\mathrm{.}7$ rad$/$s$,$ where, as usual, the plus sign indicates that the wheel is rotating in the counterclockwise direction. $($a$)$ To pass another cyclist, the rider pumps harder, and the angular velocity of the wheels increases from $21\mathrm{.}7$ to $28\mathrm{.}1ra\frac{d}{s}$ in a time of $3\mathrm{.}50$ s $.($b$)$ After passing the cyclist, the rider begins to coast, and the angular velocity of the wheels decreases from $+28\mathrm{.}1$ to $+14\mathrm{.}7ra\frac{d}{s}$ in a time of $9\mathrm{.}50$ s $.$ In both instances, $($a$)$ and $($b$),$ determine the direction and magnitude of the angular acceleration $($assumed constant$)$ of the wheels.

$($a$)$ Direction

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$($b$)$ Direction

Number

i

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