Help needed ASAP In a lab experiment, a string has a mass per unit length of 0.120 g/m. It is attached to a vibrating device and weight as shown in the figure. The vibrating device oscillates at a constant frequency of 157 Hz.

where P = 157.

What should be the three largest weights in order to produce standing waves in a string of length 42.0 cm?

this is poiselle's equation from fluid mechanic in physics. mech eng

speed of light in vacuum is 300,000 km/s

speed of light in other mediums is given by the expression v = c/n, where c is the speed of light in vacuum and n is the refractive index of medium.

for the first medium v = 200,000 km/s

  so, refractive index of medium = 300000/200000 = 1.5

    1.5 refractive index is usually for glass. so first medium is glass.

for the second medium v = 250,00 km/s

so, refractive index of medium = 300000/250000 = 1.2

    1.2 refractive index is usually for water. so second medium is water.

for the third medium v = 0 km/s

so, refractive index of medium = 300000/0 = ∞

    ∞ refractive index is usually for opaque mediums. so third medium is opaque medium.