Colonel john p. stapp, usaf, participated in studying whether a jet pilot could survive emergency ejection. on march 19, 1954, he rode a rocket-propelled sled that moved down a track at a speed of 632 mi/h. he and the sled were safely brought to rest in 1.40 s. col. john stapp and his rocket sled are brought to rest in a very short time interval. stapp's face is contorted by the stress of rapid negative acceleration. (courtesy of u. s. air force) (a) determine the negative acceleration he experienced (in m/s2). m/s2 (b) determine the distance he traveled during this negative acceleration (in m). m (c) what if? col. stapp was able to walk away from this experiment. if the human body can survive a negative acceleration five times that experienced by col. stapp, what minimum stopping time (in s) would this correspond to in the 1954 experiment?

(a)

First of all, let's convert the initial velocity from miles/hour to m/s:

Then we can find the acceleration by using the equation:

where:

v = 0 is the final velocity

u = 282.5 m/s is the initial velocity

t = 1.40 s is the time interval

Substituting into the equation,

(b) 197.7 m

We can find the stopping distance by using the SUVAT equation:

where

v = 0 is the final velocity

u = 282.5 m/s is the initial velocity

is the acceleration

d is the distance travelled while stopping

Solving for d, we find

(c) 0.28 s

In this case, the acceleration is five time that experienced in the previous experiment:

We can find the stopping time by using the equation:

where

v = 0 is the final velocity

u = 282.5 m/s is the initial velocity

Since we have the acceleration, we can re-arrange the formula to find the time:

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