I think that number five is lithium
All of the electromagnetic energy radiated from the sun (and from
other stars) is the product of nuclear fusion in its core.
Linear momentum has to be conserved. It was zero before the thread eas burned ... when nothing was moving ... so the momentum of the masses moving in opposite directions has to add up to zero. ... Momentum = mass times speed. ... In one direction, you have 5 kg times 1/5 m/s= 1 kg-m/s. ... We need 1 kg-m/s in the other direction. ... 7 kg times speed = 1 kg-m/s. ... Can you finish it from here ?
There are several possibilities. Here are a few that occur to me:
-- If Point-A is the summit of Pike's Peak, he may feel somewhat
short of breath.
-- If Point-A is his grandmother's house, he may feel a great sense
of pleasant anticipation.
-- If Point-A is his office on Monday morning, then he may feel
a tightening sensation in his chest.;
-- If Point-A is his home on Friday afternoon, then he feels the
effects of a slow and steady drop in his blood pressure.
I finer point might be put to it if we had any idea of where
Point-A is, and what it represents in the grand scheme
of things.
