A circular race course track has a radius of $500 \mathrm{~m}$ and is banked at $10^{\circ}$. The coefficient of static friction between the tyres of a vehicle and the road surface is 0.25 . Compute
(i) the maximum speed to avoid slipping
(ii) the optimum speed to avoid wear and tear of the tyres.
Q 47.13
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$
\text { Data : } r=500 \mathrm{~m}, \theta=10^{\circ}, \mu_{\mathrm{s}}=0.25, \mathrm{~g}=9.8 \mathrm{~m} / \mathrm{s}^2, \tan 10^{\circ}=0.1763
$
(i) On the banked track, the maximum speed of the vehicle without slipping (skidding) is
$
\begin{aligned}
& v_{\max }=\sqrt{\frac{r g\left(\mu_{\mathrm{s}}+\tan \theta\right)}{1-\mu_{\mathrm{s}} \tan \theta}} \\
& =\sqrt{\frac{500 \times 10(0.25+0.1763)}{1-(0.25 \times 0.1763)}} \\
& \text { MaharashtraBoardSolutions. Guru } \\
& =\sqrt{\frac{500 \times 10 \times 0.4263}{0.9559}}=\sqrt{2230} \\
& =47.22 \mathrm{~m} / \mathrm{s} \\
&
\end{aligned}
$
(ii) The optimum speed of the vehicle on the track is
$
\begin{aligned}
v_{\text {opt }} & =\sqrt{r g \tan \theta} \\
& =\sqrt{500 \times 10 \times 0.1763} \\
& =\sqrt{881.5}=29.69 \mathrm{~m} / \mathrm{s}
\end{aligned}
$
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