The Montgolfier brothers (Joseph and Etienne) were eighteenth-century pioneers of hot-air ballooning. Had they had the appropriate instruments, they might have left us a record, like that shown in Figure 5.70, of one of their early experiments. The graph shows their vertical velocity, v, with upward as positive.
(a) Over what intervals was the acceleration positive? Negative?
(b) What was the greatest altitude achieved, and at what time?
(c) This particular flight ended on top of a hill. How do you know that it did, and what was the height of the hill above the starting point?

Transcribed Image Text:

v (ft/min) 20 10 0 -10 -20 10 20 30 40 50 Figure 5.70 60 t (min)