“Then you multiply the value of time by the horizontal velocity of the ball.”
“Yes, but why?”
“Because the speed is constant in the horizontal direction.”
It wasn’t enough to have a hunch and know the right answer, or memorize how to solve the equation. You had to know why. Or the way Dad pronounced it, “Hhhhwwhy?”
This was the key. If you knew hhhhwwhy you didn’t have to memorize equations, or solve equations in the exact same way they did in the book, or cheat by tucking index cards with sample questions and answers scribbled on them in the small pocket created by the back of your graphing calculator and its case so you could secretly reference them and mechanically match the steps.
If you knew hhhhwwhy, you were ready. If you knew hhhhwwhy, it became fun, even.
By the time I was a junior in high school, friends started asking me how I could cut so many physics classes (it was right after lunch) and still manage to pass exams.
After I told them about my secret tutor, they wanted to join me for study sessions. I hesitated; I kept my American life separate from my Chinese home life, where you had to take off your shoes and watch what you said. I worried especially that my guy friends would be met with suspicion by my conservative parents, who never talked about dating.
I remember overhearing a conversation my good friend Bren was having with my dad in the kitchen.
“O.K., so they’re asking you to figure out the velocity of this vector and translate it to centripetal force on this swing and figure out the distance the ball will travel, after taking into account the friction from the ground if the ball is rolling,” Dad was saying.
“No, we haven’t learned about some of the vectors yet, so for the sake of the problem, we just take this one out,” Bren, who actually attended classes, and unlike me, knew what we had and hadn’t yet learned, explained.
