In a spiral galaxy, the bulge in the center consists of older stars, whereas the spiral arms are made of younger stars. Explain this statement.

Asap and show ! a 14 kg rock starting from rest free falls through a distance of 5.0 m with no air resistance. find the momentum change of the rock caused by its fall and the resulting change in the magnitude of earths velocity. earth mass is 6.0 * 10^24 kg. show your work assuming the rock earth system is closed.

Selma made a diagram to compare convection and radiation. which label belongs in the area marked x? must involve temperature differences between substances or objects only occurs when molecules are in direct contact involves the movement of fluids based on density differences can occur where there is little or no matter

Hydrogen atoms are excited by a laser to the =4n=4 state and then allowed to emit. what is the maximum number of distinct emission spectral lines (lines of different wavelengths) that can be observed from this system? 8 6 2 7 4 5 1 3 calculate the wavelength of the 4⟶14⟶1 transition. =λ=