So cvdebater666 calculated Quicksilver's (travel) speed to be about 2,976,000 m/s.
I believe people punch faster than they can actually run and so I'm going to say his punches are going 5952000 m/s or so.
According to a quick googling you should use the mass of 2-4 kg for the weight of the fist and part of the arm for a punch so I am using 4kg since I am arguing for QS.
So .5(4)(5952000)^2 = 70,852,608,000,000 Neutons!
= 16 934.18 tons of TNT!!!
(Also he kicked him once)