You guys are assuming there would be no transfer of energy causing sydney to splat against the inside of her own shield. I dont know if being bullet proof resistant, means she can slam herself bodily into solid objects and expect to go through them like they dont even exist. Put her in the bomb suit again, then have her ram things at gradually increasing speeds to confirm or deny this potential application please. If there is even a ten percent reduction in speed, that means if she slams into a plane going 400 mph, she will hit the wall of her shield going 40. Crunch.