Question

A man running around a circular track of radius 20m covers one complete round in 40s.

What will be the speed?​

Answer 1

Explanation:

Distance Covered in one round of a circular

track by the man = 2πr = 2 × π × 20

= 40π = 40 × 22/7

= 880/7 metre

Speed = distance/time

= 880/ ( 7 × 40 )

= 88 / ( 7 × 4 )

= 22/7 = 3.14 m/second

or 1 π m/Second

Answer 2

$\blue{\bold{\underline{\underline{Answer:}}}}$

$\green{\tt{\therefore{Speed=3.14\:m/s}}}$

$\orange{\bold{\underline{\underline{Step-by-step\:explanation:}}}}$

$\green{\underline \bold{Given :}} \\ \tt: \implies Radius(r)= 20\:m \\ \\ \tt: \implies Time(t) = 40 \: sec \\ \\ \red{\underline \bold{To \: Find :}} \\ \tt: \implies Speed(s)= ?$

• According to given question :

$\bold{As \: we \: know \: that} \\ \tt: \implies Circumference \: of \: path = 2\pi r \\ \\ \tt: \implies Circumference \: of \: path =2 \times 3.14 \times 20 \\ \\ \green{\tt: \implies Circumference \: of \: path =125.6 \: m} \\ \\ \bold{As \: we \: know \: that} \\ \tt: \implies Speed = \frac{Distance}{Time} \\ \\ \tt: \implies Speed = \frac{125.6}{40} \\ \\ \green{\tt: \implies Speed = 3.14 \: m/s} \\ \\ \bold{Alternate \: method : } \\ \\ \tt \circ \: Acceleration = 0 \: {m/s}^{2} \\ \\ \tt: \implies s = ut + \frac{1}{2} {at}^{2} \\ \\ \tt: \implies 125.6 = u \times 40 \\ \\ \tt: \implies u= \frac{125.6}{40} \\ \\ \green{\tt: \implies u =3.14 \: m/s}$