Question

The wheel of a bicycle is 70 cm in diameter. How far has it travelled in 720 revolutions of the wheel? The wheel makes 2 revolutions per second. Calculate the speed of the cyclist in kmph

Answer 1

radius is 35 cm (as radius is half of diameter)
circumference of circle is
$2\pi \times r \\ radius \: is \: 35 \\ 2 \times 3.14 \times 35 \\ 219.8$
It has done 720 revolutions
for 1 revolution distance covered is 219.8
for 720 revolutions it is
$219.8 \times 720 \\ 158256 \: cm \\ 1582.56 \: m \\ 1.58256 \: km$
1.58256 divided by 2
0.79128 kmph