Recent content by ltd5241

Thank you ! Especially you,Arildno.

Is this ∫r(a)da wrong? Why?

I want to caculate length of curve in Polar coordinate system like this: if r=r(a) then length of the curve is [SIZE="4"]∫r(a)da Is this right? if not ,why ? What's the right one ? I konw the way in rectangular coordinate system,I just want to do it in Polar coordinate system .

For 2, use the product rule. What's the rule?

1.how to prove div(A × B) = (rot A)· B - A ·(rot B) 2.d(ω1(A) × ω1(B))=?

That's what i want.And thank you all who answer my question!

Do you mean the direction is random and vibrate in all direction which is orthogonal to the light travel direction?

water vibrate up-down right? what about the one colour normal light?

What about the sunlight?

If the light move from left to right, what's the vibration direction of light wave? up-down or front-back or some other ways?

Thank you all! I've read 11. Classical Mechanics: Point Particles and Relativity,and the general part of the 14. Thermodynamics and Statistical Mechanics,i'll keep reading in your seggested sequence and look for better books. Are these books no good for teaching myself?

I want to learn these books by myself,but I don't know the sequence. Walter Greiner course of Physics - 14 Books Summary: 1 Quantum Mechanics: An Introduction 2 Quantum Mechanics. Special Chapters 3. Quantum Mechanics: Symmetries 4. Relativistic Quantum Mechanics. Wave Equations 5. Field...

Thank you! That's it.Rattleback.

Help me!A spinning blue plastic object made me sleepless. I've seen the mit online vedio course Physics I: Classical Mechanics Lecture 21 Torques, Oscillating Bodies,near the end 44:19.There is a spinning blue plastic object,the teacher spun it, it revolved then it stoped,then it revolved...