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. (a) Determine the negative acceleration he experienced. (b) Determine the distance he traveled during this negative acceleration.

(a) a = - 201.8 m/s²

(b) s = 197.77 m

Explanation:

(a)

The acceleration can be found by using 1st equation of motion:

Vf = Vi + at

a = (Vf - Vi)/t

where,

a = acceleration = ?

Vf = Final Velocity = 0 m/s (Since it is finally brought to rest)

Vi = Initial Velocity = (632 mi/h)(1609.34 m/ 1 mi)(1 h/ 3600 s) = 282.53 m/s

t = time = 1.4 s

Therefore,

a = (0 m/s - 282.53 m/s)/1.4 s

a = - 201.8 m/s²

(b)

For the distance traveled, we can use 2nd equation of motion:

s = Vi t + (0.5)at²

where,

s = distance traveled = ?

Therefore,

s = (282.53 m/s)(1.4 s) + (0.5)(- 201.8 m/s²)(1.4 s)²

s = 395.54 m - 197.77 m

s = 197.77 m