Question

A man running around a circular track of radius 20 m covers one complete round in 40 s. Calculate the
distance and displacement covered by him in 3 minutes.

​

Answer 1

In 3min.(180sec.) it will cover 4.5 rounds.

DISTANCE-

4.5(2×3.14×20)= 4.5×125.6=565.2

DISPLACEMENT-

2r= 2×20= 40

Answer 2

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

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

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

$\green{\underline \bold{Given :}}$

$\tt: \implies Radius(r)= 20\:m$

$\tt: \implies Time(t) = 40 \: sec$

$\red{\underline \bold{To \: Find :}}$

$\tt: \implies Speed(s)= ?$

• Given Question

$\bold{As \: we \: know \: that}$

$\tt: \implies Circumference \: of \: path = 2\pi r$

$\tt: \implies Circumference \: of \: path =2 \times 3.14 \times 20$

$\green{\tt: \implies Circumference \: of \: path =125.6 \: m}$

$\bold{As \: we \: know \: that}$

$\tt: \implies Speed = \frac{Distance}{Time}$

$\tt: \implies Speed = \frac{125.6}{40}$

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

$\tt \circ \: Acceleration = 0 \: {m/s}^{2}$

$\bold{Alternate \: method : }$

$\tt: \implies s = ut + \frac{1}{2} {at}^{2}$

$\tt: \implies 125.6 = u \times 40$

$\tt: \implies u= \frac{125.6}{40}$

$\green{\tt: \implies u =3.14 \: m/s}$