Question

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

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

Answer 1

The correct option is D $2,000J-5,000J$

$v=\frac{d}{t}=\frac{100}{10}=10m/s$

$K.E=\frac{1}{2}m{v}^2$

It is clear that the K.E depends on both mass and speed. Mass is not given in the question.

Suppose it lies between 40kg to 100kg

then,

$\frac{1}{2}\times 40\times {10}^2<K.E<\frac{1}{2}\times 100\times {10}^2$

$2000J<K.E<5000J$

Thus, the range of K.E lies between 2000J and 5000J