Question

Can you please show me the formulas you used in these problems? I keep using the wrong ones.

In his last ride in a rocket sled in 1955, Col. Stapp was accelerated to 632 miles per hour in 5.0 s, and then brought to a stop with an acceleration of 46.2 g, the largest acceleration voluntarily endured by a human.

a. How far did the sled move in the first phase, as it accelerated to maximum speed?

b. How far did the sled move as it came to a stop?

c. What was the force exerted on Col. Stapp by his crash harness?

Assume he had a mass of 70 kg. (You may assume this is the only significant force!)

Answer 1

(a) During the first phase-

initial velocity,

final velocity,

time taken,

using the first equation of motion-

acceleration,

Now, using the second equation of motion-

is the distance the sled moved in the first phase.

(b) In the second phase, the sled is coming to a stop, therefore the acceleration is negative-

Initial velocity in this phase is,

Final velocity,

Using the third equation of motion-

, is the distance traveled by the sled in second phase before it came to a halt.

(c) Time taken by the sled in the second phase to come to stop can be calculated using the first equation of motion-

Force exerted by the crash harness is-

where, is the change in momentum and is the time taken