The US athlete Florence Griffith - Joyner won the 100 m sprint gold medal at SeoulOlympic 1988 setting a new Olympic record of 10.54 s. Assume that she achieved her maximum speed in a very short-time and then ran the race with that speed till she crossed the line. Take her mass to be 50 kg. Assuming that the track, the wind etc. offered an average resistance of one tenth of her weight, calculate the work done by the resistance during the run.

4900 J

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-4900 J

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Zero

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50 J

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Solution

The correct option is B
-4900 J

resistive force by track/wind is in the opp. Direction of displacement

W= $\to F . \to S$ = -FS

given $F = \frac{1}{10} \times 50 \times 9.8 N$

=49

W=-49 $\times$ 100 J

W=-4900J

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The correct option is B -4900 J resistive force by track/wind is in the opp. Direction of displacement W= →F.→S = -FS given F=110×50×9.8 N =49 W=-49 × 100 J W=-4900J

The correct option is B
-4900 J

resistive force by track/wind is in the opp. Direction of displacement

W= $\to F . \to S$ = -FS

given $F = \frac{1}{10} \times 50 \times 9.8 N$

=49

W=-49 $\times$ 100 J

W=-4900J