# Search results

1. ### Clarification needed: u-sub requires combining 2 constants

Homework Statement Evaluate ∫-x/(x+1) dx Homework Equations The Attempt at a Solution I do a U-sub u=x+1 du=dx x=u-1 -∫(u-1)/u du -∫[u/u - 1/u] du -∫1 - 1/u du -[∫1du - ∫1\u du] -[u - ln(u) + C] ln(u)-u+C ln(x+1)-(x+1)+C ln(x+1)-x-1+C I combine -1 and C into a single C to get...
2. ### Kenneth Krane's Modern Physics muon example (SR)

This is the frirst SR problem in his book. I think the question is flawed. The solution assumes a speed of 3.00 E8 m/s to calculate Δt=333us since it traveled 100km. Next, 333us and 2.2us is used to solve for velocity using the time dilation formula. Velocity is reported to be .999978c...
3. ### An infinite, isotropic, homogeneous, and static arrangement collapses under gravity?

Can anyone explain this to me? If we have an infinite amount of balls arranged in a kind of cubic matrix, in an infinite and static space...how the heck would that collapse on itself due to gravity? Thanks folks
4. ### Entrance to graduate programs

I have been searching for the requirements for entry into physics graduate programs. I am seeing GRE + physics GRE + 3 LORs Is it understood that the student has a strong background in physics or mathematics or do they really not require it? I have signed up for higher mathematics...
5. ### Strange delta G question

Question: Which best describes the delta G for hydrolysis of creatine phosphate under cellular conditions in which the concentration of creatine phosphate, creatine, and phosphate all equal 1 mM at 25 degrees C. The delta G naught for the hydrolysis of creatine phosphate at 25 degrees C is...
6. ### Area/riemann sums questions

1) if you have 2 line segments making a right angle, and connect the endpoints with a line segment with an outward curve relative to the vertex, will the area inside always be irrational? 2) if you have 2 line segments making a right angle, and connect the endpoints with a line segment with an...
7. ### Inertial vs accelerating frame

I'm free-falling towards a planet. Inertial or not? I suppose this is a postulate of general relativity isn't it? When I'm studying special relativity I would say Non-inertial, but then if I think about how I cannot really tell if I am accelerating or just traveling a constant...