Recent content by little neutrino

But why is that so? __ __ __ __ __ For two letters to be the same == 26 choices For the last letter, since it can't be the same as the two letters that are the same == 26 - 1 = 25 choices No. of ways to arrange 3 letters, when 2 are the same == 3!/2! = 3 Thus no. of ways == 26 * 25 * 3 * 92 Why...

A code is generated consisting of 3 letters followed by 2 digits. Each of the 3 letters generated is equally likely to be any of the 26 letters of the alphabet. Each of the 2 digits generated is equally likely to be any of the nine digits 1-9. Find the probability that a randomly chosen code has...

Homework Statement Spaceship A of length 30m travels at 0.6c past spaceship B. Clocks in frame S' of spaceship A and S of spaceship B are synchronised within their respective frames of reference and are set to zero, so that t' = t = 0 at the instant the front of spaceship A passes the rear of...

Hmm I thought it would be symmetrical because according to the crew of A, A is stationary and B is moving at -0.384c relative to A. Thus the length of B is contracted to 0.923l0. So time taken for B to pass A is (1+0.923)l0/0.384c = 1.67 * 10-5, which is the same as (i). Is this correct?

Ohhh right! Thanks! :)

Homework Statement A pole-vaulter holds a 5.0 m pole. A barn has doors at both ends, 3.0 m apart. The pole-vaulter on the outside of the barn begins running toward one of the open doors, holding the pole level in the direction he is running. When passing through the barn, the pole just fits...

Homework Statement Two rockets are each 1000m long in their rest frames. Rocket A, traveling at 0.800c relative to the earth, is overtaking Rocket B, which is moving in the same direction at 0.600c. (i) According to the crew on B, how long does A take to completely pass? I.e. how long is it...

Ohhh I see. Thanks so much! :)

Hmm, if n >> 1, then the numerator 2n + 1 = 2n and the denominator n2(n+1)2 = n4. After simplifying this, I get the answer. But I'm still a bit confused; if I directly substitute n+1 = n (since n>>1) for the initial expression 1/n2 - 1/(n+1)2, won't I just get 0? :/

Homework Statement (a) Show that in the Bohr model, the frequency of revo-lution of an electron in its circular orbit around a stationary hydrogen nucleus is f = me4/4ε02n3h3 (b) In classical physics, the frequency of revolution of the electron is equal to the frequency of the radiation that it...

Woah that's sweet XD Thanks for the alternative solution!

Yup, I finally worked through the algebra. Thanks! :)

Sflr I was caught up with some stuff this week :/ I just figured out the algebraic manipulation after substitution of u' ; I realized that I had to observe the final expression more closely instead of blindly manipulating the algebra. Thanks so much for your help! :)

I tried substituting the Lorentz transformation for u' ux' = (ux-v)/(1-uxv/c2) into the LHS and simplifying it from there, but I couldn't derive the expression on the RHS :(

Hi. In the attached proof for Lorentz transformation for momentum http://www.colorado.edu/physics/phys2170/phys2170_sp07/downloads/lorentz_transformation_E_p.pdf, there is this step that I don't understand: 1/√1-u'2/c2 = γ(1-vux/c2)/√1-u2/c2 Can someone explain how they derived this? Thanks! :)