Question

The diameter of a wheel of a car is 70 cm. How much distance will it cover in making 50 revolutions?
(a) 350 m
(b) 110 m
(c) 165 m
(d) 220 m

Answer 1

(b) 110 m
$$\begin{gathered} \mathrm{Radius}\mathrm{of}\mathrm{the}\mathrm{wheel}=\frac{\mathrm{Diameter}}{2}=\frac{70}{2}=35\mathrm{cm} \\ \mathrm{Circumference}\mathrm{of}\mathrm{the}\mathrm{wheel}=2\mathrm{\pi r}=(2\times \frac{22}{7}\times 35)\mathrm{cm}=220\mathrm{cm} \\ \mathrm{The}\mathrm{distance}\mathrm{covered}\mathrm{by}\mathrm{the}\mathrm{wheel}\mathrm{in}\mathrm{one}\mathrm{revolution}\mathrm{is}\mathrm{equal}\mathrm{to}\mathrm{its}\mathrm{circumference}. \\ \mathrm{Distance}\mathrm{covered}\mathrm{by}\mathrm{the}\mathrm{wheel}\mathrm{in}1\mathrm{revolution}=220\mathrm{cm} \\ \therefore \mathrm{Distance}\mathrm{covered}\mathrm{by}\mathrm{the}\mathrm{wheel}\mathrm{in}50\mathrm{revolution}=(50\times 220)\mathrm{cm}=11000\mathrm{cm}=110\mathrm{m} \end{gathered}$$