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 km/h?

Answer 1

Radius = 21 m. speed = 8 km/ hr. 8 * 5/18 =20 /9m/s but , speed distance / time therefore time = distance / speed here , distance = 2 * 22/7 * 21. =132m. Time = 132*9 / 20 =59.2 s . Don't mind if this answer is wrong.

Answer 2

Given that,

The radius of a circular field, r = 21 m

Speed of a man, v = 8 km/h

To find,

How long will a man take to make a round of a circular field.

Solution,

We know that, speed of an object is equal to total distance divided by the time taken.

v = 8 km/h = 2.23 m/s

Using formula for speed.

$v=\dfrac{d}{t}\\\\\text{Where t is time taken and d is circumference of the circular field}\\\\t=\dfrac{2\pi r}{v}\\\\t=\dfrac{2\times \dfrac{22}{7}\times 21}{2.23}\\\\t=59.19\ s$

Hence, it will take 59.19 seconds to make a round on a circular field.