*To help you Learn more , I will try my best to update some such posts !*

**Q: How small are atoms?**

^{-10}meter across—that’s 0.0000000001 meter. An atom has a tiny core made of protons and neutrons. This core, called the nucleus, is even tinier, typically about 10

^{-15}meter (0.000000000000001 meter) across. It is surrounded by a kind of cloud of particles called electrons. This cloud brings the size of the atom up to about 10

^{-10}meter. Notice that the nucleus is roughly 10,000 times smaller than the mostly empty electron cloud, so the atom is in fact mostly empty space!

**Q: Why is chaos theory interesting?**

**Q: How would a fusion reactor differ from the nuclear reactors we currently have?**

*deuterium*(heavy hydrogen) and fuses them together to make larger ones such as helium. If the binding energy of the two deuterium nuclei is greater than that of the final larger helium nucleus, it can be used to generate electricity.

**Q: What causes friction?**

**Q: Why don’t heavy objects fall faster than light ones?**

*F*=

*km*/

*r*

^{2}.

*F*is the force the Earth’s gravity exerts on the object,

*k*is the mass of the Earth times Sir Isaac Newton’s constant,

*m*is the mass of the object, and

*r*is the distance from the object to the center of the Earth. The force of gravity is proportional to the mass of the object—the greater the mass, the greater the force.

*a*=

*F*/

*m*. (We’ll ignore air resistance here.) According to this equation, an object’s acceleration is proportional to the force exerted on the object—the greater the force, the greater the acceleration. But the acceleration is also inversely proportional to the mass of the object—the greater the mass, the smaller the acceleration. We saw above that a greater mass means a greater force of gravity, but that effect is balanced by the fact that a greater mass means a lesser acceleration.

**Q: What are some good ways to motivate or interest my 13 year old in math?**

*Mathematical Puzzles and Diversions*) that I recall from my youth. They are collections of great articles from when he used to write for

*Scientific American*. They were fantastic. If you can find those, or others like them, that would also be a great start.

**Q: What is an isotope?**

**Q: What is the speed of light?**

**Q: In math, what’s the difference between the mean, the median, and the mode?**

**Q: When people talk about the “new math,” what do they mean?**

**Q: Why is it important that scientists be open-minded?****Q: On a piano, if you go from middle C up an octave to the next higher C, what happens to the frequency of the sound wave? And what are overtones?**

**Q: I would like to know the speed that gravity travels. I am making the assumption that since the Sun’s gravity affects the Earth and vice versa and so on, that gravitons have to move and therefore they have a speed.**

**Q: Can you settle a question? I always thought you could not go the speed of light because the faster you go, the greater your mass would become until you reach a point where your mass is infinite and therefore you would need an infinite amount of energy to move you to light speed. My friend says that as you approach the speed of light your mass decreases and you can never go the speed of light because you can never have no mass. Which is right?**

**Q: Has there been a successful fusion experiment other than a hydrogen bomb? What was the setup?**

*Scientific American*in August 1998.

**Q: What is superconductivity?**

**Q: Talk of exhausted fossil fuels and the need for alternative fuel sources is already rampant. One of the most enticing solutions (at least in Hollywood films) seems to be fusion. How do you do what is commonly called cold fusion at room temperature?**

**Q: In a rotating wheel the linear velocities of different particles of the wheel point in all different directions. The only unique direction in space associated with the rotation is along the axis of rotation, perpendicular to the actual motion. Could you explain this mathematically?**

**Q: Why does water expand when it freezes?**

**Q: What is calculus, and what practical uses does it have?**