All are moving at the same speed. Rank in order, from largest to smallest, the tensions T1 to T4.
1 Answer

tension T = mv²/r
so case 1 is simply mv²/r
and case 2 is mv²/(2r)
and case 3 is 2mv²/r
and case 4 is 2mv²/2r = mv²/r
so largest to smallest is
T3 – T1 – T4 – T2
or
T3 – T4 – T1 – T2
and maybe you could put
T3 – T4 = T1 – T2
Hope this helps!