Answer:
Step-by-step explanation:
According to the principle of conservation of mechanical energy, the total mechanical energy of a pendulum remains constant throughout its motion. The mechanical energy consists of potential energy and kinetic energy.
At the bottom of its swing: When the pendulum reaches the bottom of its swing, all of its potential energy is converted into kinetic energy. Therefore, the kinetic energy at the bottom of its swing will be equal to the potential energy at the top.
Given that the pendulum has 15 J of potential energy at the top, the kinetic energy at the bottom will also be 15 J.
With 8 J of potential energy: Using the principle of conservation of mechanical energy, we can say that the total mechanical energy remains constant. Therefore, the sum of potential energy and kinetic energy will be constant.
Since the pendulum has 8 J of potential energy, the kinetic energy can be calculated by subtracting the potential energy from the total mechanical energy. However, without knowing the total mechanical energy, we cannot determine the exact value of the kinetic energy.
If it loses 2 J to heat: In this case, the total mechanical energy of the pendulum will decrease by 2 J due to the energy lost as heat. Therefore, the kinetic energy will also decrease by 2 J, while the potential energy remains unchanged.
If we assume the initial kinetic energy was K J, after losing 2 J to heat, the new kinetic energy will be K - 2 J.
Please note that without additional information, such as the total mechanical energy or the initial kinetic energy, we cannot determine the exact values in the second and third scenarios.