Kids are inquisitive about everything and they ask all manner of questions. They think their mom and dad know everything too. Hence the repeated questions if the answer is not satisfactory or evasive.
It's not only questions. Kids also show their curiosity by their actions. When the kiddo was still a toddler, he was so fascinated with round or circular objects like wheels and dials especially. He would try to turn it with his little finger and spend hours just turning and investigating its motion.
When he laid eyes on the clock on the wall, he was mesmerised. He finally managed to touch the pendulum with the help of a step ladder ( with a little help from the dad). He loved it. The clock no longer hangs on the wall. Yes, it was removed as we were concerned that it might come off the hook due to the kiddo's sometimes persistent and exuberant play.