A mass of 0.8 kg is fixed at a vertical spring with an unknown spring constant. When spring is released from rest, it extends to 15cm before it stops. As the system oscillates with Simple Harmonic Motion (SHM) the weight is pulled down 20cm further downward and being released. 1. What is the spring constant?
2. What is the total energy of the system?
3. What is the angular frequency of spring?
4. What is the velocity of the system at x=10cm below equilibrium position? ​

gas and liquid

cant without the picture! ?

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.