1.how is the law of conservation of energy demonstrated by the movement of the pendulum?
2. what force slows down and eventually stops pendulum?
3. at what point in the pendulums swing is its gravitational potential energy highest?

1. Law of conservation of energy states that energy cannot be created, nor destroyed, for example, windmills take kinetic energy(movement energy) and convert it into electrical energy using gears and a generator as well as the blades.

so this supports it because the pendulum never reaches the same height twice unless you reset it so the energy is always getting less and less and not randomly getting back onto the pendulum.

2.Gravity, friction and air resistance slow it down as well

3. at the top, potential energy is the amount of energy something has relative to the amount it can disperse before stopping, for example, a book on a shelf has more potential energy than that of a book on a table, this is because when the shelf book falls it will create more energy than the table book.