Question

How long will jhon take to make a round of a circular field of radius 21 m cycling at the speed of 8 km/h?

Answer 1

Here, Radius = 21m.....
Speed = 8 kmph
$= 8 \times \frac{5 \: m}{18 \: s} \\ = \frac{20m}{9s}$
Total Distance to Travel = Circumference of The Circle.... =
$2\pi r \\ = 2 \times \frac{22}{7 } \times 21m \\ = 132m$
So, Now We have.....
Speed AND Distance.....
And AS WE KNOW.....
Speed = Distance ÷ Time.....
So, Time = Distance ÷ Speed
$= > time = 132m \div \frac{20m}{9s} \\ = > \frac{132m \times 9s}{20m} \\ = > 59.4s$
THEREFORE, Jhon will take 59.4 seconds to make a round of that circular field.....

THERE YOU GO!!!