A block moving horizontally on a smooth surface with a speed of 40 m s - 1 splits into two parts with masses in the ratio of 1 : 2 . If the smaller part moves at 60 m s - 1 in the same direction, then the fractional change in kinetic energy is :

Step-by-step solution

m × 40 = 2 3 m v + m 3 × 60 120 = 2 v + 60 v = 30   m s - 1 Now K i = 1 2 × m × 40 2 = 800 m K f = 1 2 × 2   m 3 ( 30 ) 2 + 1 2 × m 3 × ( 60 ) 2 = 1 6   m ( 1800 + 3600 ) = m ( 5400 ) 6 = 900 m Δ K E K i = 900 m - 800 m 800 m = 1 8