What is the new angle of the light ray after Lorentz transformations?

[Felpudio]

[Mentor's note: This question was originally posted and responded to in a non-homework forum, therefore it does not have the usual homework template.]

Hey, don't know how to solve this:

In an inertial frame S, consider a light ray on the XY plane forming a 60 degree angle with the x-axis. What will the new angle be, when S moves in the x direction with a c/2 velocity?

Thanks.

 

[Orodruin]

Perhaps this should have been posted in the homework forum.

Consider the light ray starting at the origin of S at time $t = 0$ (with moving system denoted S', you already said S was the original inertial frame, you cannot call the moving frame S as well). Where will it be a time $t = T$ later based on the information you have? What do you get if you Lorentz transform these two events to S'?