Category Archives: Engineering

Q: Is it more efficient to keep keep a swimming pool warm or let it get cold and heat it up again?

The original question: I’m having a debate with my wife that I think you can help us resolve.  We have a swimming pool in our back yard.  It has an electric heater, which we set to keep the pool water … Continue reading

Posted in -- By the Physicist, Engineering, Physics | 14 Comments

Q: If the world is a giant magnet, how come we can’t build a repelling magnet that can float?

Physicist: Three big reasons: 1) The Earth’s magnetic field is hella weak 2) it’s so big and roughly uniform that there’s no reason for a magnet to go one direction or the other 3) floating a magnet in a magnetic … Continue reading

Posted in -- By the Physicist, Engineering, Physics | 2 Comments

Q: Is it possible to parachute to Earth from orbit?

Physicist: Yes and no, but mostly no. It’s certainly possible to parachute safely to Earth from the top (or nearly the top) of the atmosphere, but this question isn’t about parachuting from space it’s about parachuting from orbit.  An orbit … Continue reading

Posted in -- By the Physicist, Engineering, Physics | 8 Comments

Q: How do I know my windmill is on straight?

The original question was: I got quite the challenge from my father in law. The problem is well defined, but I’m having difficulties finding a meaningful answer. The reason why he asked me is because I’m an engineering student and … Continue reading

Posted in -- By the Physicist, Engineering, Equations, Geometry, Math | 4 Comments

Q: Could the tidal forces of the Sun and Moon be used to generate power directly?

The original question was: If a machine enclosed in a building could, as I think it could, detect the tidal forces of the sun and moon upon the Earth could the effect be used to extract useful energy from those … Continue reading

Posted in -- By the Physicist, Astronomy, Engineering, Physics | 5 Comments

Q: Does opening a refrigerator cool down the room?

Physicist: Briefly yes, or no, not at all.  If you think of the room as including the inside of the refrigerator, then opening the door does nothing.  Otherwise, it does almost nothing.  But ultimately, if you leave the door open … Continue reading

Posted in -- By the Physicist, Engineering, Entropy/Information, Physics | 23 Comments