Question

A running boy has the same kinetic energy as that of a man of twice his mass. If the speed of the boy is \(14.14\ \text{m s}^{-1}\), the speed of the man is

• A. \(1.414\ \text{m s}^{-1}\)
• B. \(0.25\ \text{m s}^{-1}\)
• C. \(10\ \text{m s}^{-1}\)
• D. \(3\sqrt{2}\ \text{m s}^{-1}\)
• E. \(0.5\ \text{m s}^{-1}\)

Hint:

If kinetic energies are equal, compare \(mv^2\) directly instead of writing \(\frac12\) every time.

Answer 1

The Correct Option is C