Recent content by eifphysics

The resistive force, or drag, f of the air is the force by the medium that oppose an object in its opposite direction of motion, given by: $$f=f(v)\hat { v }$$ The function f(v) varies with v in a very complicated way. However, at lower speed(lower than the speed of sound), it is a good...

For general chemistry, Caltech's Chemical Principles is a good source and free for download. For physics, you could check out University Physics with Modern Physics.

How to change my e-mail account on PF. Thanks in advance.

What you said is spinon in condensed matter physics. A Higgs-related production predicts a new spin 1/2 particle, which is analogous to spinon in condensed matter physics

It is somehow related to spinon, and share a similar production process. By the way, even if I make a mistake, you don't need to sound so harsh as if I am crazy. We are all sincere physics learners.

What is demi-bosons, or demons in particle physics. I searched Google but got no serious answer.

Steel ships can float on water, but steel is definitely denser than water. Maybe we can borrow that idea.

"125 Physics Projects For the Evil Genius" is a great book for this purpose. It has different levels of experiments, but very suitable for high school students.

For a IB course project project, you can go to www.sciencebuddies.org for ideas on topic.

Inertia is not a kind of counterforce. It is a measure of how hard it is to change an object's speed and direction(thus its acceleration). From Newton's second law F = ma, we can see that inertia is proportional to the object's mass. For example, it is harder to change a train's motion than to...

By the way, 340m/s is about the speed of sound in air. I think whether or not we can see the object depends on its speed as well as its apparent size . We have a good chance seeing a supersonic aircraft, but not a bullet.

No, here i is just an example. I couldn't tell what i is from your information. Is this the whole problem?

Linear transformation can be written into a matrix form. When you times a matrix with a unit basis vector, if the unit basis vector has a 1 as its first element and 0s as its other elements, then you obtain the first column of the matrix as a result. Keep doing this you can calculate all...

To answer part(c), just plug in corresponding unit basis vectors into the linear transformation formula, and you will obtain each column of the matrix.

a = v2/r = gcosθ. gcosθ is the largest centripetal force, component of gravity normal to the sphere surface. If θ is larger v will be too big to maintain in circular motion. Then use conservation of mechanical energy to obtain a second equation for v and θ.