JEE Main Physics question

Physics Work, Energy and Power JEE Main

If a man increases his speed by 2 m/s, his K.E. is doubled. The original speed of the man is [Pb. PET 2002]

(A)(1+2√2) m/s
(B)4 m/s
(C)(2+2√2) m/sCorrect
(D)(2+√2) m/s

Answer: (C)

Solution

½m(v+2)² = 2(½mv²) ⟹ (v+2)² = 2v² ⟹ v+2 = v√2 ⟹ v(√2−1) = 2 ⟹ v = 2/(√2−1) = 2(√2+1) = 2√2+2.

Question ID VK-153966