Which of the following is NOT a unit of length in the English system?

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=

The law of the conservation of momentum says that the total momentum of any closed and isolated system cannot

Acar of mass 800kg is moving at a speed of 2.2m/s.