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An Olympic sprinter runs 100 m in 10 s. The athlete’s kinetic energy is most reasonably estimated to lie in which interval?

1. 200 J to 500 J
2. 2 × 10⁵ J to 3 × 10⁵ J
3. 20,000 J to 50,000 J
4. 2,000 J to 5,000 J

Correct answer: 2,000 J to 5,000 J

Solution

v = 100 m / 10 s = 10 m/s. With a sprinter mass of about 70 kg, KE = 0.5*70*10^2 = 3500 J, which lies in the 2,000 J to 5,000 J range.

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