Department of Pre-University Education, KarnatakaPUC Karnataka Science Class 11

The 200 M Free-style Women'S Swimming Gold Medal at Seoul Olympics in 1988 Was Won by Heike Friendrich of East Germany When She Set a New Olympic Record of 1 Minute and 57⋅56 Seconds. - Physics

Sum

The 200 m free-style women's swimming gold medal at Seoul Olympics in 1988 was won by Heike Friendrich of East Germany when she set a new Olympic record of 1 minute and 57⋅56 seconds. Assume that she covered most of the distance with a uniform speed and had to exert 460 W to maintain her speed. Calculate the average force of resistance offered by the water during the swim.

Solution

$\text{ Time taken to cover 200 m, t } = 1 \min 57 . 56 \text{ seconds = 117 . 56 s }$

$\text{ Power exerted by her, }$

$\text{ P = 460 W }$

$P = \frac{W}{t}$

$\text{ Work done, W = Pt } = 460 \times 117 . 56 J$

$\text{ Again, W = Fs }$

$\Rightarrow F = \frac{W}{s}$

$= \frac{460 \times 117 . 56}{200}$

$= 270 . 3 \text{ N } \approx 270 \text{ N }$

∴ Resistance force offered by the water during the swim is 270 N.

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HC Verma Class 11, 12 Concepts of Physics 1
Chapter 8 Work and Energy
Q 22 | Page 133