BIO Blackout?? A jet fighter pilot wishes to accelerate from rest at a constant acceleration of 5 g to reach Mach 3 (three times the speed of sound) as quickly as possible. Experimental tests reveal that he will black out if this acceleration lasts for more than 5.0 s. Use 331 m/s for the speed of sound. (a) Will the period of acceleration last long enough to cause him to black out? (b) What is the greatest speed he can reach with an acceleration of 5g before he blacks out?

Solution 20E Given that, initial speed u = 0 Final sapeed v = 3 × 331 m/s v = 993 m/s Acceleration a = 5g From the equation, v = u + at 993 = 5g × t t = 993/5g s t = 20.26 s (a) Therefore,the pilot will take 20.26 s to reach the Mach 3 speed. This is more than 5.0 s. So, he will black out. (b) ime to black out is = 5.0 s Acceleration is = 5g The speed he reaches before black out is = 0 + 5g × 5 m/s = 25 × 9.8 m/s = 245 m/s Therefore, 245 m/s is the required speed.