I think it might be A. I’m sorry if I’m wrong
The momentum should be .5 because you multiply the mass and velocity to get momentum
Explanation:
Given that,
Initial speed of the billiard ball 1, u = 30i cm/s
Initial speed of another billiard ball 2, u' = 40j cm/s
After the collision,
Final speed of first ball, v = 50 cm/s
Final speed of second ball, v' = 0 (as it stops)
Let us consider that both balls have same mass i.e. m
Initial kinetic energy of the system is :

Final kinetic energy of the system is :

The change in kinetic energy of the system is equal to the difference of final and initial kinetic energy as :
So, the change in kinetic energy of the system as a result of the collision is equal to 0.
When light crosses the interface between a medium with higher refractive index and a medium with lower refractive index, there is a maximum value of the angle of incidence after which there is no refraction, but all the light is reflected, and this maximum value is called critical angle.
The critical angle is given by

where n1 is the refractive index of the first medium while n2 is the refractive index of the second medium. In our problem, n1=1.33 and n2=1.58, so the critical angle is
Answer:

Explanation:
The enegy of a single photon is given by:

where
h is the Planck costant
c is the speed of light
is the wavelength of the photon
In this problem,

so the energy of one photon is

1 mole of photons contains a number of Avogadro of photons:

therefore, the total energy of 1 mole of these photons will be
