What type of forces accelerate masses?

What are atoms of the same element with varying number of neutrons

Amichelson interferometer operating at a 600 nm wavelength has a 3.02-cm-long glass cell in one arm. to begin, the air is pumped out of the cell and mirror m2 is adjusted to produce a bright spot at the center of the interference pattern. then a valve is opened and air is slowly admitted into the cell. the index of refraction of air at 1.00 atm pressure is 1.00028.how many bright-dark-bright fringe shifts are observed as the cell fills with air?

Which lists the amplitudes of sound waves from these sources in order from greatest to least? busy roadway, kids whispering, average home chainsaw, diesel truck, rustling leaves kids whispering, vacuum cleaner, jet airplane library, conversational speech, music from speaker