Why does my wall clock keep stopping?

A clock that is out of beat is likely to stop because the pendulum is not receiving the optimum impulses to keep it swinging. If it's badly out of beat it will stop within a few minutes. If it's only slightly out of beat it could run for days but will eventually stop earlier than it should.

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Regarding this, how do you tick a clock?

Then, what is the energy in a pendulum? All of the energy in the pendulum is kinetic energy and there is no gravitational potential energy. However, the total energy is constant as a function of time.

What happens when you increase the length of a pendulum?

Increasing the length of the pendulum's string and increasing the angle of displacement both increase the distance the pendulum must travel in a single period, increasing its potential energy at its maximum height, and therefore the maximum velocity at its lowest point. Where does the energy in a pendulum go? Once the weighted end of the pendulum is released, it will become active as gravity pulls it downward. Potential energy is converted to kinetic energy, which is the energy exerted by a moving object. An active pendulum has the most kinetic energy at the lowest point of its swing when the weight is moving fastest.

And another question, what does it mean when the pendulum swings back and forth?

This back and forth motion is called "oscillation." Its position is said to oscillate back and forth. The period is the amount of time it takes the bob to make one round trip. If the pendulum bob is pulled back and released, it returns to the hand that released it after a time interval equal to one period. In respect to this, when a pendulum swings at which point is potential? B. If kinetic energy is highest at the bottom of the pendulum, then that is where potential energy is the lowest. So potential energy would be highest when the pendulum is at its highest point on either side of its motion where it is stationary for an instant.