Question

an athlete completes one round of a circular track of diameter 300m in 80 seconds.find the distance covered and the displacement at the end of 3 minutes 20 seconds

Answer 1

Answer:-

Given:-

Diameter of the Circular track = 300 m [∴ Radii = d/2 = 300/2 m = 150 m]

Time taken = 80 s

An Athelete completes the whole track in 80 s.

To Find:-

Distance covered after covering 3 m 20 s (200 s).

Displacement after covering 3 m 20 s (200 s).

3m 20s = 3 × 60s + 20s

= 180s + 20s

= 200s

____________________...

Distance:-

After completing 200 s, the Athelete completes:-

200/20 rounds

= 10 rounds

Length of 1 round:-

(2πr) units (Circumference of circ.)

= 2 × π × 150 m

= 300π m

∴ The Athelete will cover :-

300π m × 10

= 3000π m

≈ 3000 × 3.14 m [pi's approx. val.]

≈ 30 × 314 m

≈ 9420 m ...(Distance - 1st Ans.)

Displacement:-

After completing 10 rounds, it will stay in the starting point. Or, the final and initial position will be same.

Since displacement is the shortest distance from the initial to the final position,

∴ Displacement = 0 m ...(Ans. 2)