What type of circuit is illustrated

The image shows a pendulum in simple harmonic motion the pendulum starts at a and swing to e

What are two different ways you could find the value of a? explain these methods.

How does a circuit breaker protect a refrigerator? a. when the current is too high, a metal strip in the fuse melts and opens the circuit. b. when the resistance is too high , a re-settable which opens a circuit c. when the current is too high , a re-settable switch opens the circuit d. when the resistance is too high a metal strip in the fuse melts and opens the circuit