Question

An athlete completes on round of a circular track of diameter 200m in 40s. What will be the distance covered and th displacement at the end of 2 minutes 20s ?​

Answer 1

Explanation:

An athlete completes a round of a circular track of radius 100m. In 40s.

So distance covered = 2 X 22/7 X 100

=4400/7

Displacement is 0

Answer 2

GIVEN :

Diameter of a circular track = 200 m.

Radius, $\sf r \: = \: \dfrac {200}{2} \: = \: 100 \: m$

Time taken, t = 40 sec.

TO FIND :

Distance covered = ?

Displacement = ?

FORMULA :

$\sf Speed \: = \: \dfrac {distance}{time}$

Circumference of the circle = $2 \pi r$

SOLUTION :

2 min 20 sec = 140 sec.

Number of rounds = $\sf \dfrac {140}{4} \: = \: 35$

→ Distance covered = $\sf 35 \times \: circumference.$

→ Distance covered = $\sf 35 \times 2 \times 22 \times 100.$

→ Distance covered = 2200 m.

→ Displacement = 200 m. because it will again return to its initial position.

$\therefore$ The distance covered at the end of 2 min 20 sec is 22000 m.

Now, Convert meter into kilo meter.

$\sf \dfrac {22000}{1000} \: = \: 22 \: km$

$\therefore$ The displacement will be 200 m.