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 of cycle.

Answer 1

Given:
Diameter of the wheel = 60 cm
Radius of the wheel =Diameter/2 = 60/2= 30 cm
Circumference of the wheel = 2πr
= 2 × 22 7 × 3
= 1320 /7 cm

Distance covered in 1 revolution = Circumference = 1320 /7 cm
Distance covered in 140 revolutions = (1320 /7) × 140 =
= 1320 × 20
=  26400 cm
= 26400/100 m
[ 1 cm = 1/100 m ]
= 264 m

Distance covered in one minute = Distance covered in 140 revolutions = 264 m
Distance covered in one hour (60 minutes) = 264 × 60 = 15840 m = 15840/1000 = 15.84 km
[1 m = 1/1000 km ]

Speed per hour = 15.84 km /hr

Hence, the speed with which the boy is cycling is 15.84 km / hr

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