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A jet pilot takes his aircraft in a vertical loop (Fig. 5–38).

  1. If the jet is moving at a speed of 840 km/h at the lowest point of the loop, determine the minimum radius of the circle so that the centripetal acceleration at the lowest point does not exceed 6.0 g’s.
  2. Calculate the 78-kg pilot’s effective weight (the force with which the seat pushes up on him) at the bottom of the circle, and
  3. at the top of the circle (assume the same speed).
Problem 12.

Figure 5-38.

Giancoli, Douglas C., Physics: Principles with Applications, 7th Ed., ©2014. Reprinted by permission of Pearson Education Inc., New York.
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Quick Answer: 
  1. $930\textrm{ m}$
  2. $5400\textrm{ N}$
  3. $3800\textrm{ N}$

Giancoli 7th Edition, Chapter 5, Problem 12



For part c, how can you be certain to use 233.33 m/s as your velocity if this is the velocity give by the problem for the lowest point of the loop? I solved the problem by using 6.0g as my radial acceleration (i got the correct answer but I'm not sure why). Thank You.

Oops I misread the part where it said "same speed".