Q. A LASER is operating at a frequency f = 6.1*10^14 Hz. A)Calculate the momentum of the photon emitted by the laser. B)A helium atom flies towards the laser at a speed of v = 3.5 m/s.During one laser pulse the gold atom absorbs on average 5 photons.Find the speed the helium atom after one laser pulse.Treat the interaction between photons and the helium atom as an inelastic collision.Use m=4.0u for mass of the helium atom. ATTEMPT: wavelength λ= c/f = 3×10^8/6.1×10^14 ≈492 nm. ⇒Total momenta of 5 photons in 1 pulse =5×h/λ =5×6.63×10^-34/4.92×10^-7 = 5×1.35×10^-27 = 6.75×10^-27 kg.m/s Again, like in the previous question i posted, i can't figure out how to find the speed of the helium atom. (Here i can't divide the momenta of 5 photons by the mass of the He atom) BTW the mass of the He atom will probably be :- M(He)=4×1.6605×10^-27 = 6.64×10^-27 kg That's as far i can get.I guess what i must do is deal with the conservation of linear momentum but i am not sure.Any suggestions?I really must complete these questions in time.