8 The new Lockheed SR-72. Travels 4598 mph. Has to drop over 3000 feet per second in order to not fly off in to space (youtu.be) posted 3 years ago by FortheGenerations 3 years ago by FortheGenerations +10 / -2 18 comments share 18 comments share save hide report block hide replies
A level plane, a bubble I. A tube. Making a level surface is not a difficult task, and may be done for this experiment. There are many ways to measure 90 degrees when building an experiment.