A world’s land speed record was set by Colonel John P. Stapp when in March 1954 he rode a rocket-propelled sled that moved along a track at 1020 km/h. He and the sled were brought to a stop in 1.4 s. In terms of g, what acceleration did he experience while stopping?

#### Solution:

### Acceleration is equal to the change in velocity over the total time, a=\frac{\triangle v}{\triangle t}. Let us first convert 1020 km/h to m/s. 1020 km/h=283.33m/s. Now, we can substitute these values into our equation, which gives us:

### a=\frac{283.33m/s}{1.4s}

### a=202.4 m/s^2

### To write this in terms of g, we simply divide this answer by 9.8 m/s^2. Thus:

### a=\frac{202.4m/s^2}{9.8 m/s^2}g=21g

###### This question can be found in Fundamentals of Physics, 10th edition, chapter 2, question 32.