Question

the radii of two wheels of a railway engine are 120 cm and 8 cm respectively if the larger wheel makes 7540 revolutions to travel a certain distance find the number of the revolution made by smaller wheel to cover the same distance used pie 3.14<br />​

Answer 1

Distance travelled by larger wheel..

Given

Larger radius = 120 cm

Smaller radius = 8 cm

no. of revolutions of larger wheel (n1) = 7540

let no. revolutions of smaller wheel (n2) = ?

$distance \: \: covered by \: \: larger \: \: wheel \: \\ = n _{1}(2\pi \: r _{1} )\\ = 7540 \times 2\times \pi \times 120 \\ = 1809600\pi \\ or \\ 5682144 \: \: cm$

According to question

Distance covered by larger wheel = distance covered by smaller wheel..

$n _{2} (2\pi \: r _{2}) \: = n _{1} (2\pi \: r _{1}) \\ n _{2} (2\pi \times 8) = 1809600\pi \\ \\ n _{2} = \frac{1809600\pi}{2\pi \: \times 8} \\ \\ = 113100$