Come for the cat video, stay for the science…

This showed up in my Facebook feed the other day.

As I watched this video about six or seven times in a row, you know I couldn’t help but consider the physics behind the poor kitty’s plight. We’ve discussed how an object only changes its motion (starts moving, stops moving, changes speed, changes direction) if an overall force acts on it. When a cat jumps off the floor, what’s applying the force that allows her to start moving upward?

Oddly enough, the floor is.

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Scientific Pet Peeve #1: Mass vs. Weight

Everyone has their pet peeves; unsurprisingly, at least a few of mine are science related.

Most people wouldn’t give a second thought to hearing someone say that something “weighs” twenty kilograms. I physically shudder whenever I hear or read such phrasing- and when I was a textbook editor, said shuddering was usually channeled straight into my red pen. Some of the first things you learn or teach in an intro physics class are the facts that mass is measured in kilograms, weight is measured in Newtons (or pounds), and mass and weight are not the same thing.

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I am a Physics Ninja, Part Two

Many of the contestants on the American spinoff of Ninja Warrior are avid participants in parkour. To these traceurs (and  yes, I did need Google to learn that word), the whole world is an obstacle course. To nerds, the whole world is a science demonstration. This is the second in a series of posts that shows what happens when these two worlds collide.

2) Newton’s Second Law: The acceleration of an object is inversely proportional to the mass of the object and directly proportional to the net force applied to the object. Mathematically, this is expressed as Force=mass x acceleration. The less mass an object has, the easier it is to get it to speed up. If you push harder, you’ll speed the object up more.

This is probably the most intuitive of Newton’s Laws, and commentators have referred to it (if not by name) on both Wipeout and Ninja Warrior. Continue reading

I am a Physics Ninja, Part One

I’ve always loved TV shows that feature obstacle courses. As a child I watched Fun House, Finders Keepers, and several incarnations of Double Dare. (Even if I hadn’t mentioned my twenty-seventh birthday, this information would place my date of birth squarely in the mid-eighties.) In recent years I’ve gotten into Wipeout and Ninja Warrior. The former makes me laugh, the latter makes me get off my butt and do push-ups during commercials, and both, naturally, make me think about physics- especially Newton’s Laws of Motion.

1) Newton’s First Law: Objects at rest tend to stay at rest; objects in motion tend to stay in motion.

That’s the version you’ve always heard. A more specific version would go like this: Continue reading