Answer :
When a hammer drives a nail into a board, it does work on the nail, resulting in the hammer's mechanical energy being less after the impact due to the transfer of kinetic energy. The correct answer is C. Less, because the hammer has done work.
The question relates to mechanical energy and work in a physics context, specifically during the interaction between a hammer and a nail. When a hammer drives a nail into a board, it transfers some of its kinetic energy to the nail, doing work on the nail. As the kinetic energy is transferred from the hammer to the nail, the hammer's mechanical energy decreases. Therefore, the correct answer is C. Less, because the hammer has done work. This is due to an inelastic collision where some of the kinetic energy is not conserved in form of kinetic energy but could be converted into other forms such as thermal energy or energy needed to deform the nail and the wood.
