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Question
The US athlete Florence Griffith-Joyner won the 100 m sprint gold medal at Seoul Olympics in 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. What power Griffith-Joyner had to exert to maintain uniform speed?
Solution
Given:
Distance covered by her, s = 100 m
Time taken by her to cover 100 m, t = 10.54 s
Mass, m = 50 kg
The motion can be assumed to be uniform.
To maintain uniform speed, she had to exert 4900 J of energy to overcome friction.
Power exerted by her to overcome frcition,
\[\text{P} = \frac{\text{W }}{\text{ t } }\]
\[ = \frac{4900}{10 . 54} = 465 \text{ W } \]
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