A bicycle wheel of radius 35 cm is making 25 revolutions in 10 secs. At what speed in km/hr is the cycle moving ?

radius of the bicycle = 35

we know that the circumfrence of the circle = 2piR

and total revolution is = 25

so total moving path is = 25 *2piR = 25*2 * 22/7 *35 = 5500cm =5500 / 1000 =5.5 km

we know that speed is = distance / time (time =10s =10 /3600 hr =1 /360 hr)

so speed = 5.5 /1 /3600 =5.5 *3600 = 55 /10 *3600 = 19800 km / hr