One of the problems of wind tunnel testing at airspeeds near sonic speed is the large effect on the flow conditions of a small change in the test configuration. Suppose sonic velocity in a wind tunnel with a 10 ft2 test section cross section is 1000 ft/s. Estimate the percentage change in the test section air speed when a model of 0.1 ft2 cross section is placed in the test section, if the air speed in the empty tunnel is 100, 900 and 1100 ft/s.