Question

An athlete in the olympic games covers a distance of 100m in 10s. His kinetic energy can be estimated to be in the range:

• A. $20,000J-50,000J$
• B. $2,000J-5,000J$
• C. $200J-500J$
• D. $2\times {10}^{5}J-3\times {10}^{5}J$

Answer 1

Answer: (B)

$2,000J-5,000J$

The speed of the athlete=$v=\frac{Distance}{Time}$

$=\frac{100m}{10s}=10m/s$

Thus the kinetic energy of the athlete=$\frac{1}{2}m{v}^2$

The mass of a man may vary between $40kg$ and $100kg$.

Hence the kinetic energy may range between,

$\frac{1}{2}\times 40\times {10}^{2}J=2000J$ and $\frac{1}{2}\times 100\times {10}^{2}J=5000J.$

Range,
$2000J-5000J$