A bullet of mass 50 ~g is fired with a speed 100 ~m / s on a plywood and emerges with 40 ~m / s . The percentage loss of kinetic energy is :

Step-by-step solution

aligned K _ i & = 1 2 ~m (100)^2 ~K _ f & = 1 2 ~m (40)^2 % loss & = | K _ f - K _ i | K _ i 100 & = | 1 2 ~m (40)^2- 1 2 ~m (100)^2 | 1 2 ~m (100)^2 100 & = |1600-100 100| 100 =84 % aligned