Force between a hydrogen nucleus and an unknown nucleus.

A H nucleus & a nucleus of yet an unknown atom are stationary at 5.0x10^-10 m apart, Hydrogen atoms mass is mH = 1.7x10^-27kg with an electric charge of e = 1.6x10^-19 C. The Coulomb constant is Ke = 9.0x10^9 Nm^2 C^-2 and that the gravitational constant is G = 6.7x10^-11 N m^2 kg^-2. Is the force between the hydrogen and the unknown atom is attractive or repulsive. What is the electric charge of the unknown atom in coulombs with notation and as a whole number integer of the multiple of the charge of the H nucleus, e. Assumption is that the whole number is the atomic number of the unknown nucleus such as protons within it. The magnitude of the gravitation force between the H nucleu... click for more

Spin 1/2 system - Pure and mixed ensembles

Consider a PURE ensemble of a spin 1/2 system. Suppose , and the sign of are known. Show how we may determine the state vector. Why is it unnecessary to know the magnitude of ? ===================================== Consider a MIXED ensemble of a spin 1/2 system. Suppose [Sx], [Sy] and [Sz] are known. Show how we may construct the 2x2 density matrix which characterizes the ensemble.

Cosmology- How far away is the galaxy in mega parsecs?

If a galaxy has a luminosity of 6.6x10^39 W and a brightness measured as 1.25x10^-11 W m^-2, How far away is the galaxy in mega parsecs? An absorption line of the element beryllium is observed in the spectrum of the galaxy above as lying 509.4 nm. What is the speed of the recession of the galaxy in km s^1 assuming that the speed of light is c = 3.00 x 10^5 km s^-1 And what is the value of the Hubble Constant?

Astronomy - I know the value of one parsec in metres but how is it calculated?

(1) I know the value of one parsec in metres but how is it calculated? (2) Can you give a brief note on Hubble's Constant?

Show that the average of the Hamiltonian is an upper bound to the ground state energy.

Show that the average of the Hamiltonian is an upper bound to the ground state energy.