A Closer Look at a 400 m Athletics Track Class 9

A Closer Look at a 400 m Athletics Track Class 9

Question 1.

A Closer Look at a 400 m Athletics Track Class 9

Above Figure depicts a 400 m athletics track. You can see two straight sections of length 84.39 m each, and two curved portions, which are semicircles with a common Centre (points A and B); the innermost semicircle on each side has radius 36.5 m. The width of each lane is 1,22 m. Let an athlete make one complete ; circuit of the track. What is the total distance she runs?

Answer:

Let the athlete run at a distance of 0.3 m from the inner border of the track.

There are two straight parts, each of length 84.39 m.

∴ Total straight distance

= 2 × 84.39 = 168.78 m

Now, Radius of each semicircle

= 36.5 + 0.3 = 36.8 m

Two semicircles together form a complete circle

Circumference of complete circle

= 2πr = 2 × 3.1416 × 36.8 = 231.22 m

Total distance run by the athlete

= 168.78 m + 231.22 m = 400 m.