An athlete in the olympic games covers a distance of $100 \mathrm{~m}$ in $10 \mathrm{~s}$. His kinetic…

An athlete in the olympic games covers a distance of $100 \mathrm{~m}$ in $10 \mathrm{~s}$. His kinetic energy can be estimated to be in the range
  1. $200 \mathrm{~J}-500 \mathrm{~J}$
  2. $2 \times 10^5 \mathrm{~J}-3 \times 10^5 \mathrm{~J}$
  3. $20,000 \mathrm{~J}-50,000 \mathrm{~J}$
  4. $2,000 \mathrm{~J}-5,000 \mathrm{~J}$

Solution

Approximate mass $=60 \mathrm{~kg}$ Approximate velocity $=10 \mathrm{~m} / \mathrm{s}$ Approximate $\mathrm{KE}=\frac{1}{2} \times 60 \times 100=3000 \mathrm{~J}$ $\mathrm{KE}$ range $\Rightarrow 2000$ to 5000 joule

Asked in: JEE Main 2008

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