2. explain how potential energy, kinetic energy, and total mechanical energy change form in a swinging pendulum, and how the speed changes as a pendulum swings back and forth without friction. include the pendulum at its initial position, when it is moving downward, when it is at its lowest point, and when it is on the rise again.

In swinging pendulum if air friction or air resistance is not present then we can say that sum of its kinetic energy and potential energy will always remains constant

Here it will show that kinetic energy of pendulum will convert into potential energy and vice versa during its to and fro motion

Like here we can say that if the pendulum is released from rest from its one of the extreme position then its kinetic energy will keep on increasing till it will reach at the lowest position while its potential energy is decreasing to the least at the lowest position

Now once it again start rising towards other extreme then again its potential energy start increasing and kinetic energy again start decreasing

At the other extreme position the kinetic energy of the pendulum becomes zero again and potential energy is maximum again

So here since no air friction so we can say that mechanical energy of the pendulum will remain constant at all the time

the answer for apex is the lowest