A particle moves on a circular path of radius $r=$ $0.8 \mathrm{m}$ with a constant speed of $2 \mathrm{m} / \mathrm{s}$. The velocity undergoes a vector change $\Delta \mathbf{v}$ from $A$ to $B$. Ex press the magnitude of $\Delta \mathbf{v}$ in terms of $v$ and $\Delta \theta$ and divide it by the time interval $\Delta t$ between $A$ and $B$ to obtain the magnitude of the average acceleration of the particle for
$(a) \Delta \theta=30^{\circ},(b) \Delta \theta=15^{\circ},$ and
(c) $\Delta \theta=5^{\circ}$. In each case, determine the percentage difference from the instantaneous value of acceleration.