Question

dr. john was a u.s air force officer who studied the effects of extreme deceleration on the human body. On December 10, 1954 he rode a rocket sled, accelerating from resr to a top speed of 282 m/s (1015 km/h) in 5.00 s, and was brought jarringly back to rest in only 1.40 s! Calculate his (a) acceleration and (b) deceleration. Express each in multiples of g (9.80 m/s2) by taking its ratio to the acceleration of gravity.

Answer 1

The value of accelerating the rocket sled from rest to 5 sec with the speed of,

$v_1=282ms^{-1}$

Thus, the acceleration of the rocket sled is,

$\begin{gathered} a=\frac{v_1-0}{5-0} \\ a=\frac{282}{5} \\ a=56.4ms^{-2} \\ a=5.8\text{g} \end{gathered}$

where g is the acceleration due to gravity.

$g=9.8ms^{-2}$

The rocket sled is declerated to the rest in 1.4 s from the speed v1,

Thus, the decleration of the rocket sled is,

$\begin{gathered} d=\frac{0-v_1}{1.4} \\ d=\frac{-282}{1.4} \\ d=-201.43ms^{-2} \\ d=-20.6g \end{gathered}$

Hence, the rocket sled is accelerated at 5.8g and decelerated at -20.6g.