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KCET · Physics · Motion In One Dimension

An athlete runs along a circular track of diameter 80 m . The distance travelled and the magnitude of displacement of the athlete when he covers \(3 / 4\) th of the circle is (in m)

  1. A \(60 \pi, 40 \sqrt{2}\)
  2. B \(40 \pi, 60 \sqrt{2}\)
  3. C \(120 \pi, 80 \sqrt{2}\)
  4. D \(80 \pi, 120 \sqrt{2}\)
Verified Solution

Answer & Solution

Correct Answer

(A) \(60 \pi, 40 \sqrt{2}\)

Step-by-step Solution

Detailed explanation

Given, diameter, \(d=80 \mathrm{~m}\)
\(\therefore \quad r=40 \mathrm{~m}\)

Distance travelled after completion of \(\frac{3}{4}\) revolution
\(=\frac{3}{4} \times 2 \pi r=\frac{3 \pi}{2} \times 40=60 \pi \mathrm{~m}\)
Displacement \(=\sqrt{r^2+r^2}=r \sqrt{2}=40 \sqrt{2} \mathrm{~m}\)