Recent content by adkinje

Is it correct that the age of a star, such as the sun, is calculated by measuring the amount of helium made from fusion? If so, how do we know if that the star didn't form from a cloud that already had helium in it?

Problem: A 2.4-kg object on a frictionless horizontal surface is attached to one end of a horizontal spring of force constant k=4.5 kN/m. The other end of the spring is held stationary. The spring is strecthed 10 cm from equilibrium and released. find the system's total mechanical energy...

I almost forgot the diagram. Attached.

A straight rod of negligable mass is mounted on a frictionless pivot (see attached diagram)Blocks having masses m_1,m_2 are attched to the rod at distances l_1,l_2. (a) Write an expression for the gravitational potential energy of the blocks-Earth system as a function of the angle \theta made...

A fixed point charge of +2q is connected by strings to point charges of +q and +4q (see attached diagram), Find the tensions T_1 and T_2. For T_2, I start summing the forces on the +4q point charge. F_{net,4q}=F_{q}+F_{2q}+T_2 0=F_{q}+F_{2q}+T_{2} T_2=-(F_{q}+F_{2q}) Is this the...

lol, DUH the tension! I can't believe I left that one out. I pulled it togther and obtained the given expression. Thanks for your help.

Two point particles, each of mass m and charge q are suspended from a common point by threads of length L. Each thread makes an angle \theta with the vertical. (I attached a diagram to help). I must show that q=2L\sin\theta\sqrt{\frac{mg}{k}\tan\theta} I start out by writing the force...

thanks, that's what I was looking for.

Lenny Susskind from standford university has several lectures on youtube explaining both lagrangian and hamiltonian mechanics. They are just alternative formulations of the laws of motion and classical mechanics in general. Just find stanford's page on youtube and then find the playlist (modern...

I've been following along with Lenny Susskinds lectures on modern classical mechanics on youtube. at 34:30 he writes a few translation formulas on the board: delta X = - epsilon Y delta Y = epsilon X It's not obvious to me why these equations are true. I can't seem to find a...

I have been annoyed by a problem that I can't figure out. The topic is work and kinetic energy (chapter 6 in the sixth edition of physics for scientist and engineers by Paul A. Tipler). Problem 63 pg. 199 A single horizontal force F acts in the +x direction on a mass m. The intial velocity...