Q. The maximum speed with which a car is driven round a curve of radius 18 m without skidding (where, $g = 10ms^{- 2}$ and the coefficient of friction between rubber tyres and the roadway is 0.2) is
A) 36.0 $km{\ h}^{- 1}$
B) 18.0 $km{\ h}^{- 1}$
C) 21.6$\ km{\ h}^{- 1}$
D) 14.4$\ km{\ h}^{- 1}$
Explanation
(c) Here, $v_{\max} = ?,r = 18\ m,g = 10\ ms^{- 2}$
$\mu = 0.2$
$\frac{mv_{\max}^{2}}{r} = F = \mu R = \mu mg$
$v_{\max} = \sqrt{\mu rg} = \sqrt{0.2 \times 18 \times 10} = 6\ ms^{- 1}$
$= 6 \times \frac{18}{5}km{\ h}^{- 1} = 21.6\ km\ h^{- 1}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.