So You’re Underwater: Why Do You See That Circle of Light Above You?
Have you ever sat on the bottom of a swimming pool and pondered your watery ceiling? Most of the surface is a sheet of light blue, and you can’t see …
dot physics
What Kind of Battery Would You Need to Power a Lightsaber?
Melting an ice cube takes 3.34 x 105 joules per kilogram. So a single ice cube with a mass of 50 grams would take 16,700 joules. You can already see …
Can You Really Run on Top of a Train, Like in the Movies?
Just because you see something done in a movie, that doesn’t mean you should try it yourself. Take, for example, a human running on top of a moving train. For …
Can You View a Round Solar Eclipse Through a Square Hole?
If you live in the US and missed the last total solar eclipse in 2017, good news! You’re about to get another chance. There will be a total solar eclipse …
How Do Heat Pumps Work?
Now stretch it really hard and quickly hold it to your upper lip, which is sensitive to temperature. You will feel that it’s warmer than it was before. That’s because …
How to Convince Your Flat-Earth Friends the Earth Is Round
Illustration: Rhett Allain You can see that we have a right triangle with the hypotenuse equal to the distance from the observer’s eyes to the center of the Earth (R …
Why the Polar Vortex Is Bad for Balloon Artists
It’s been crazy cold this week, even down where I live in Louisiana, thanks to an outbreak of a polar vortex. This frigid air is bad for all kinds of …
School of Rock: The Physics of Waves on Guitar Strings
The rubber band example does indeed have two nodes—they are at the ends of the rubber band where your fingers hold it. We only have half a wavelength in the …
How to Measure the Impact From a Collision
Not only do I get the “shape” of the acceleration curve for the colliding cart, but I also get a maximum acceleration of –6.67 meters per second squared. With that …
Could a Cockroach Survive a Fall From Space?
There’s some cool stuff going on here. Notice that for the objects with air resistance, they all reach incredibly high velocities as they fall in the upper atmosphere where they …