NCERT science chapter 8 page 112 class 9th
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Given, Diameter (d) of the track = 200m
Time taken for 1 round of the track = 40s (t)
Distance travelled in 1 round (s) = circumference of track
= 2π r
= πd
= π x 200
(s) = 200π m
Hence, speed of athlete along the track (V) = s/t = 200π/40
= 5π m/sec
Time interval = 2 minutes 20 sec (Given)
= 140 seconds
∴ distance travelled in 140 sec is given by s = v x t
= 5π x 140
= 5 x 22/7 x 140
= 2200 m
The no of revolutions completed = 2200m/200π.
= 2200/(200x22/7) = 3.5
Athlete has completed 3.5 revolutions.
∴ Displacement of athlete = diameter of track = 200m.
Time taken for 1 round of the track = 40s (t)
Distance travelled in 1 round (s) = circumference of track
= 2π r
= πd
= π x 200
(s) = 200π m
Hence, speed of athlete along the track (V) = s/t = 200π/40
= 5π m/sec
Time interval = 2 minutes 20 sec (Given)
= 140 seconds
∴ distance travelled in 140 sec is given by s = v x t
= 5π x 140
= 5 x 22/7 x 140
= 2200 m
The no of revolutions completed = 2200m/200π.
= 2200/(200x22/7) = 3.5
Athlete has completed 3.5 revolutions.
∴ Displacement of athlete = diameter of track = 200m.
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