Air Force Col. John P. Stapp was a pioneer in the study of the effects of large, rapid accelerations and decelerations on humans, as well as one of the early designers and advocates for pilot/passenger safety harnesses in planes and automobiles in the late 1940s and early 1950s. In many of the rocket sled experiments that he conducted, Stapp himself volunteered to ride the sled. On 10 December 1954, Stapp rode a jet-powered sled that achieved a maximum speed of 282.4 m/s (632 mph!), setting a land speed record for this achievement. After reaching peak velocity, the sled was rapidly decelerated, coming to rest in a mere 1.4 s.
(a) Calculate the average (negative) acceleration that Col. Stapp experienced as the sled came to a stop. How many g €™s is this?
(b) Find the distance Stapp traveled during the time it took to brake the sled from its maximum speed to rest. 

Because the acceleration of the sled as it was brought to a stop was not constant, the average acceleration computed in part (a) is smaller than the maximum (negative) acceleration that Col. Stapp suffered. On-board measurements showed that Stapp survived up to 46.2 g€™s of acceleration during the final moments of his run (see Table 1.3).

Acceleration Description (g) (m/s) Freely falling body (on the Moon) 1.6 0.16 Freely falling body (on Earth) 9.8 Space shuttle (maximum) 29 Drag-racing car (average for 0.25 mile) 32 4.2 Highest (sustained) survived by human without injury 245 46.2 Clothes-spin cycle in a typical washing machine 400 41 Tread of a typical car tire at 65 mph 2,800 285 Click beetle jumping 3,920 400 Bullet in a high-powered rifle 2,000,000 200,000 Mean acceleration of a proton in the Large 1.86 X 109 1.9 108 Hadron Collider