i found this in the syllabus:
-''Show an understanding of the origin of the upthrust acting
on a body in a fluid''
what does that mean???
-''Recognise that, for a perfectly elastic collision, the relative
speed of approach is equal to the relative speed of
separation''
and could someone briefly explain this and give an example, how are the questions diiferent from the normal m1u1 +m2u2=m1v1 + m2v2
?