Aplane lamina occupies the region in the xy-plane between the two circles x2 + y2 = 4 and x2 + y2 = 49 and above the x-axis. find the center of mass of the lamina if its mass density is σ(x, y) = σ0 x2 + y2 kg/m2.

Aphoton is absorbed by an electron that is in the n = 3 state of a hydrogen atom, causing the hydrogen atom to become ionized. very far away from the nucleus, the released electron has a velocity of 750,000 m/s. what was the wavelength of the absorbed photon?

How many neutrons does element x if it’s atomic number is 28 and its mass number is 87

(a) if the pressure in gas is doubled while its volume is held constant, by what factor do (i) vrms and (ii) change? (b) is it possible to boil water at room temperature (20oc) without heating it? explain.