A lot of people have wondered why Miley Cyrus would want to ride on a wrecking ball wearing nothing but her underwear, and sometimes even less. We at Physics Buzz took a few moments to chat with Miley* and discovered it's really all about the physics.
PB: Miley, we may be reading too much into your Wrecking Ball video, but you appear to love pendulums.
MC: You're not reading too much in to it at all.
PB: I mean, you seem to really love them.
MC: That's right.
PB: Really, really, really love them . . .
MC: OK, maybe you are reading too much into it. It's true I dig simple harmonic motion, though, which is what pendulums are all about, especially when they're performing small amplitude motions like the wrecking ball did when I was riding on it.
PB: Did you use an actual wrecking ball on a crane for the videos.
MC: I wish I could tell you that we did, but it's pretty obvious from the vid that we didn't.
PB: How so.
MC: From the oscillation period.
MC: From the time it takes to swing back and forth once. It's way too short a period. If you had a crane with a long chain, the ball would swing very slowly. I figured it would be too slow for the rhythms we were shooting for. So I asked for a shorter chain.
PB: Wouldn't the weight of the ball slow it down, even for a short chain?
MC: Not at all. You see, the period of a pendulum - the time it takes to swing from one side to the other and back - depends only on the pendulum length, not the mass. That's the real reason I was riding on it - to show that the total mass doesn't affect the motion.
MC: If you watch the video, you can see one complete oscillation starting at a minute and eighteen seconds into the video. It takes about 3.45 seconds. I'm not going to do the math for you, but you should be able to calculate the length of the pendulum pretty easily, and it's about 3 meters.
PB: What's that in feet?
MC: I don't do archaic units. I'm all about SI.
PB: What's next for Miley Cyrus?
MC: I plan to continue my musical exploration of classical physics. I'm thinking ballistic motion. I've got my people looking into a trebuchet
MC: It's like a catapult, but way cooler.*We never actually spoke to Miley. But we can pretend.