Final answer:
The pendulum will have 50 J of kinetic energy at the bottom of its swing, equivalent to its initial potential energy, according to the conservation of mechanical energy principle.
Step-by-step explanation:
The question is about the relationship between potential energy and kinetic energy in a pendulum system. According to the conservation of mechanical energy principle, in a closed system with no external work done or non-conservative forces, the total mechanical energy remains constant. This implies that when a pendulum has reached its highest point, all of its energy is in the form of potential energy. As the pendulum swings downward and reaches the bottom of its arc, this potential energy is converted into kinetic energy. At the bottom of its swing, assuming no energy is lost to air resistance, friction, or other non-conservative forces, the kinetic energy of the pendulum would be equal to its initial potential energy.
Therefore, if a pendulum has 50 J of potential energy at the highest point, it will have 50 J of kinetic energy at the bottom of its swing. The correct answer to how many joules of kinetic energy the pendulum has when it has 50 J of potential energy is: A) 50 J.