Question

A boy is cycling such that the wheels of the cycle are making 140 revolutions per minute. if the diameter of the wheel is 60 cm, calculate the speed in km per hour in which the boy is cycling.

Answer 1

no. of revolutions=140/min
diametre of wheel=60
1km=1000metres
so find curve surface area of wheel
radius of wheel=d/2=60/2=30
now formula curve surface area of spherical wheel= 4(22/7)rsquare
$4(22 \div 7) {30}^{2} =$
then divide the 1000m by the no of revolutions /min
then mutiply it by the curve surface area of spherical wheel