A man running has half the kinetic energy of a boy of half his mass. The man speeds up by 1 ms −1 and then has KE as that of the boy. What were the original speeds of man and the boy?

May 11, 2022

by Ezee_Notes

with no comment

Physics Problems

Question: A man running has half the kinetic energy of a boy of half his mass. The man speeds up by 1 ms −1 and then has KE as that of the boy. What were the original speeds of man and the boy?

(A) $\sqrt{2}ms^{-1};2\sqrt{2}-1ms^{-1}$

(B) $\left( \sqrt{2}-1\right) ms^{-1},2\left( \sqrt{2}-1\right) ms^{-1}$

(D) None of the above

Answer: Option (C)

Solution:

A man running has half the kinetic energy of a boy of half his mass. The man speeds up by 1 ms −1 and then has KE as that of the boy. What were the original speeds of man and the boy?