Physics at Home Archive - Page 4

Balloon Analogy in Cosmology - Feb 1, 2011

Quasars are the most distant objects we can see from Earth. Their light reaches us from billions of years in the past. Astronomers know how far they really are from us because the light we see is dramatically redshifted, meaning they are moving away from us astonishingly fast. See the Balloon Analogy in Cosmology to learn more about the expansion of the universe and how astronomers use redshift to measure distances in space. Find out how you can paste galaxies on a balloon and make a model of how the universe expands.

Doppler Physlet - Dec 1, 2010

Security note:
Once you have clicked on the "simulation" link below, be sure to read the Java Security Advisory before running the simulation: To do that, click the "Read now" button on the yellow band near the top of the PhET page.

Try the Physlet simulation from Davidson College to investigate the shockwaves and Doppler effect produced by objects moving at various speeds--in particular, at speeds below and above the speed of sound.

Laser Applications - Nov 1, 2010

Lasers are everywhere, from the supermarket to your CD player. Learn about even more applications at Laser Applications, and be sure to check out the links on this Laserfest webpage.

Near-Earth Object Program - Oct 16, 2010

Asteroids are usually shown between the orbits of Mars and Jupiter, but they also swing in as far as Earth's orbit, and frequently. At the time of this writing, astronomers have identified 1156 potentially hazardous asteroids, so-called because of their large size and close projected approach to Earth.

- To learn more about asteroid detection and impact risk, check out the NASA's Near-Earth Object Program.
- For daily updates about the Earth's local environment, read

U.S. Department of Energy: Energy Efficiency & Renewable Energy - Oct 1, 2010

Beyond the search for renewable energy sources, a complementary approach is to save energy by using it more efficiently. See this California state government website to find out how changes to your home and your lifestyle can help. To learn more, visit U.S. Department of Energy: Energy Efficiency & Renewable Energy.

(This feature was updated on July 25, 2013.)

The Physics Classroom: Refraction of Light - Sep 16, 2010

Use this simulation to explore how light waves bend when they go from one medium into another, like from air into water.

Konigsberg Bridge - Sep 1, 2010

If you enjoy solving puzzles, try the seven bridges challenge.
- This problem helped lead the mathematician Leonhard Euler to develop new mathematical fields, graph theory and topology. See Konigsberg Bridge to learn more.
- Also see the Wikipedia page for variations on this problem.

Splash (fluid mechanics) - Aug 16, 2010

Investigate splashes by dropping different-sized objects into containers of water. Also, you can squeeze drops out of a medicine dropper to make splashes on hard surfaces or on water or milk. (Be sure to do this activity with an adult.) To find out what happens if you drop a half-brick into water, see the photograph at the bottom of Splash (fluid mechanics).

Water on the Move - Aug 1, 2010

Using the instructions on Water on the Move, you can create a model with everyday materials that shows how the water moves as a wave passes by. To visualize the movement of all the water in a wave, see the third animation on this Kettering University page.

Soap Bubbles - Jul 16, 2010

Playing with soap bubbles can be fun and educational for people of all ages.

- Try this PBS activity to see what kind of soap films you can make inside of a geometrical wire frame.  
- Also see this album for photos of big bubbles.

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