"Tricky questions" that help to understand physics

Here are two "tricky questions" that are really interesting to help understand physics.

  1. Attach a tennis ball to string, and swing it over your head. The ball follows a circular path. Release the string. What path does the ball follow?
  2. The speed of light is 300,000 km per second, typically shown as the letter c. Take two pieces of wire each 300,000 km long. Place a light bulb and a battery 1 meter apart. Connect the light bulb to each wire. Before connecting the battery, stretch out the wire as far as you can on each side. Now connect the battery. How long until the bulb lights up? 0.5 seconds, 1 sec, 2 secs, or 1/c secs?

Why are these "trick questions"? Because of the assumptions we usually make when thinking about questions like these. Picking apart these assumptions reveals a lot about how physics works.

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