Recent content by cracking

I think it's a proof for norm 2 and 3. For any n, n-1 it's the same essentially. First consider R2. Note (x^2+y^2)^1/2 > (x^3+y^3)^1/3 is equivalent to [1+(y/x)^2]^1/2 > [1+(y/x)^3]^1/3 Assume y/x < 1 without losing generality, then from [1 + ...] > 1 one sees [1+(y/x)^2]^1/2 >...

Thank you for your suggestion tiny-tim. I don't quite agree with your method. But I still tried it as follows. A, C have no chance to give a force balance (2 forces are in the same direction). I used the balance of B and got 3/(xA - xB)^2 = 4/(xB - xC)^2, where x is the coordinate. Taking...

Yes I agree with collinsmark that for example PE(A,B) + PE(A,C) belongs to KE of A,B,C --- not A alone. Actually an easy calculation tells me that the center of mass, which remains fixed in this closed sytem, is at 12r/25 to the left of particle b (that is between a&b). Then obviouly the final...

thanks. I tried this but I have 3 quantities va, vb, vc to determine. The final total kinetic energy KE = PE(a,b)+PE(b,c)+PE(c,a), in addition to the momentum conservation equation ma va + mb vb + mc vc = 0 only give 2 restrictions on them. So I come to a case in which...

Homework Statement Three positive point charges (with charge and mass given) A (+3q, 2m),B (+q, m) ,C(+4q, 7m/31) can move in a line under the coulomb repelling of one another. The movement begins when all are at rest. Initial distance are (left to right lie A, B, C) AB = r, BC = 2r. Then...

Thank you mathman!

Hi I'm studying decay of atomic nucleus. Alpha and beta rays are essentially particles and their path are easily traced. But high frequency gamma rays easily penetrate metal foils, and I wonder that how gamma rays are practically detected and measured in lab experiments? Is photo-electric...