JEE Main Physics question
If a man speeds up by 1 ms⁻¹, his KE increases by 44%. His original speed in ms⁻¹ is
Answer: (C)
Solution
½m(v+1)² = 1.44×(½mv²) ⟹ (v+1)² = 1.44v² ⟹ v+1 = 1.2v ⟹ 0.2v = 1 ⟹ v = 5 ms⁻¹.
If a man speeds up by 1 ms⁻¹, his KE increases by 44%. His original speed in ms⁻¹ is
½m(v+1)² = 1.44×(½mv²) ⟹ (v+1)² = 1.44v² ⟹ v+1 = 1.2v ⟹ 0.2v = 1 ⟹ v = 5 ms⁻¹.