2. a student carries a glass cube whose length of the edge (l) is 4.425 ��. the density of the glass is 3.755 g/cm3 . she drops the cube, and a piece having a mass of 19.40 g breaks off. to repair the cube, student adds plastic having a density of 2.355 g/cm3 and reshapes the cube to its original shape and size. (a) what is the volume of the plastic part? (b) what is the volume of the composite object? (c) calculate the volume of the glass. (e) calculate the mass of the glass. (f) what is the mass of the composite cube? (g) calculate the density of the new composite cube.

magnitude and direction

a.   mass number from atomic number

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.