said was this: that so long as both William and the car were traveling at the same rate of speed William would have no weight, and consequently he would remain floating in the middle of the car. But if at any time William were to travel faster than the car, then he would regain a certain amount of weight."
"But did n't you just remark that the earth would always attract William just as much as it does the car, and so would cause him to fall at the same speed?"
"Yes."
"Then how could he travel faster than the car?"
"Listen. I have already told you that, in spite of my efforts to produce a perfect vacuum in the tube, I was unable to get rid of all the air. Now, air, as you know, presents a high resistance to objects traveling at a great velocity. This air, although highly rarefied, will, when William is traveling at his greatest speed, retard the car considerably."
"Yes; but it will retard William, too."
"Not in the least. It is the outside of the car that will strike against this air and be checked. William, snug inside his car, will not feel the great wind thus produced. The car will fall more
