Answer:
A pendulum works by converting energy back and forth, a bit like a rollercoaster ride. When the bob is highest (furthest from the ground), it has maximum stored energy (potential energy). ... So as the bob swings (oscillates) back and forth, it repeatedly switches its energy back and forth between potential and kinetic.
True, both humans and animals alike do have critical periods of development
The "meters" measurements refer to the diameter of the objective (the main big-moose lens or mirror).
But light collection depends on the AREA of the objective, and that means the SQUARE of the diameter.
So if you double the 'size' if the telescope, it gathers FOUR TIMES as much light as before.