Periodic relationships

Question

What are some examples of periodic relationships found around your house. It could be periodic motion, or another periodic relationship.

1. Describe an example that is periodic but not sinusoidal. (other than a tick of a clock)
2. Describe two examples that are both periodic and sinusoidal. (other than a clock)

Answer 1

My sprinklers turn on every day at 6:00 am. My water softener does a cleaning cycle each week. My car has an oil change reminder that comes on every 6,000 miles. My alarm clock goes off daily at my wake-up time. My computer does a virus scan daily at 2:00 am. These are all periodic but not sinusoidal.

An example of periodic and sinusoidal is my air conditioner. It comes on daily when it gets warm. The hotter it gets, the more it cools. Then it turns off until the next day.