Which of the following is a valuable part of the scientific method?

Idon’t know the answer to it and am stuck.

Why does a smaller car get better gas mileage than a bigger one?

The steel pipe ab has a 102-mm outer diameter and a 6-mm wall thickness. knowing that arm cd is rigidly attached to the pipe, determine the principal stresses and the maximum shearing stress magnitude at point k. (round the final answers to one decimal place.) given: f = 10 kn