Ahydrogen atom, initially at rest, absorbs an ultraviolet photon with a wavelength of λ=121.3nm. part a: what is the atom's final speed if it now emits an identical photon in a direction that is perpendicular to the direction of motion of the original photon?
part b: what is the atom's final speed if it now emits an identical photon in a direction that is opposite to the direction of motion of the original photon?

Explanation:

Momentum of a photon

= h / λ

Where h is plank's constant and λ is wave length of photon

h = 6.6 x 10⁻³⁴ Js and λ = 121.3 x 10⁻⁹ m

momentum of photon

=

= 5.44 x 10 ⁻²⁷ Ns

Momentum of hydrogen atom

= 5.44 x 10 ⁻²⁷ Ns

When hydrogen atom emits another photon in perpendicular direction , according to Newton's second law , it acquires additional momentum of equal magnitude in opposite direction to the direction of emission of photon. Hence it has two similar momentum in perpendicular direction.

The resultant momentum

= x 5.44 x 10⁻²⁷

= 7.7 x 10⁻²⁷ Ns

B ) When hydrogen atom emits another photon in opposite direction , according to Newton's second law , it acquires additional momentum of equal magnitude in opposite direction to the direction of emission of photon. Hence it has two similar momentum in acting in the same  direction.

The resultant momentum

= 2 x 5.44 x 10⁻²⁷ Js.

= 10.88 x 10⁻²⁷ Js

iron would move it is magnetic there is a mag field around the current in the wire

the order for strong to weak forces such as

strong nuclear force → electromegnetic force → weak nuclear force → gravitational force

the fundamental forces are those forces that act between to objects or element to make interactions. there are four types of fundamental forces such as strong and weak nuclear forces (due to protons and electrons), electromagnetic force (due to the motion of electrons) and gravitational force (due to orbital movement of the planet). if these forces are arranged on the basis of their maximum strength then the order is

strong nuclear force → electromegnetic force → weak nuclear force → gravitational force