Question

As shown in the diagram below, a proton (p), mass 1 u, travelling in the +x direction with

speed vpi, collides elastically, not head-on, with a stationary deuteron (d) with mass 2 u. (Here u means
the atomic mass unit. 1 u = 1.66 x 10-27 kg, but you may not need this number if you can get it to cancel
out of your equations). After the collision, the proton is observed to be moving in the +y direction.

Answer 1

As soon as I saw the opening words "As shown in the diagram below ...",
something told me that when I opened the question, there would be no
diagram below. So I opened the question. I was not shocked, and my
expectations were not shattered.

Give us the diagram below, and we'll see what we can do.