One example of power from a non–renewable resource, that has less of an effect on the environment than burning fossil fuels, would be geothermal power. hydropower. nuclear power. wind power.

Geothermal, hydro, and wind power are all examples of renewable resources.  Nuclear power is the only one here listed as non-renewable.  Nuclear power is also relatively cleaner and safer compared to other  non-renewable resources.  

For example, coal, petroleum, and natural gasses are all non-renewable resources that release carbon dioxide and other greenhouse gasses when burned.  On the other hand, nuclear power doesn't release any carbon dioxide or greenhouse gasses, because it doesn't rely on the burning of fossil fuels.

the motion of a pendulum is a classic example of mechanical energy conservation. a pendulum consists of a mass (known as a bob ) attached by a string to a pivot point. as the pendulum moves it sweeps out a circular arc, moving back and forth in a periodic fashion.