Question

how long will a man take to make a round of a circular field of radius 21 m cycling at the speed of 8 kilometre per hour

Answer 1

radius = 21 m
circumference of the circle
$= 2\pi \: r$

$= 2 \times \frac{22}{7} \times 21 \: \: \: m$
distance = 132 m


we know ,

$speed \: = \frac{distance}{time}$
$time \: = \frac{distance}{speed}$
8 km per hour = 2.2m/s

$time = \frac{132}{2.2}$


time = 60 seconds or 1 minute.

Answer 2

circumference of circle = 2 * π * radius

= 2 * 22/7 * 21

= 132cm

time = distance / speed

= 132 / 8

=16.5

=16.5 * 60

=990min