A bullet of mass 20 g enters a fixed wooden block with a speed of 40 m s ⁻¹ and comes to rest inside it. Determine the change in internal energy during the process.

Step-by-step solution

The initial kinetic energy of the bullet is given by K_ i = 1 2 mv² . Substituting the given values, m = 20 g = 0.02 kg and v = 40 m s ⁻¹ : K_ i = 1 2 0.02 (40)² K_ i = 0.01 1600 = 16 J The final kinetic energy of the bullet is K_ f = 0 since it comes to rest. According to the law of conservation of energy, the loss in kinetic energy is converted into the internal energy of the system. Change in internal energy U = K_ i - K_ f = 16 J - 0 = 16 J .