Visitors to a Renaissance Festival need not leave physics in the present day – on the contrary, science is all around. The main difference is that (human) muscle power generally substituted in olden tymes for purposes we moderns use electricity.
The Trebuchet uses counterweights and elbow-grease to accomplish what artillery do today. To manufacture all the swords for sale, Ren Festival forges need to be busy. Compare the muscle power need to stoke the coals
and hammer on an anvil
with a modern “Man at Arms”
Finally, while we might imagine that nothing could be more modern than the sound of a sonic boom, Medieval
PS. If you want to get in character but your friends are sticklers for anachronisms, remember that you can never go wrong in any era as a Steampunk Timetraveler