inertia

I have never been happy with Newton's first law

Many textbooks are pumped up about Newton's 3 laws of motion. For me, not so much. First, (as many other's point out) these are really Newton's ideas about force. Second, the first law is pretty much a special case of the second law. Here are the first two laws (in my words): Newton's First Law: The natural state of an object is constant motion. Yes. I know that is not how it is normally written. Newton's Second Law: The rate of change of an object's speed is proportional to the amount of net force on the object and inversely proportional to the mass of the object. This could also be…

I have always wanted to ask a question like this - but never found the right test for it. Perfect for a blog. Question: Suppose you are in your car at a stop light behind a truck. The truck is pulling a trailer with a rollable tractor on it. When the light turns green, the truck starts to accelerate. However, the cable holding the tractor to the trailer breaks and the tractor starts to roll off the trailer. You are right behind the trailer. What do you do? Do you have an answer yet? You should probably come up with one quickly. That tractor is rolling off now. I will put the answer…

Ruff Ruffman and Inertia Makes it Happen

Dear Ruff Ruffman, My kids really like your show. However, there is a problem. You promote it like it is science, but the content keeps having mistakes in it. Previously, I pointed out your mistake about in infrared thermometer (if can't remember, you said the thermometer measures the temperature with a laser. In fact, the laser is just used to aim.) So, you see, I don't just like to randomly attack people. The problem is that you are saying "hey look at science" but your science is wrong. I suggest you either a) stop pretending to be a science show or b) get a science advisor (I am…

Water Bottle Camera Mount for stability

Better technology sometimes causes problems. In this case, technology has made video cameras really small. Small? That's a problem? Well, the problem (as I discussed previously) is that small cameras are not stable and make "shaky" videos. Well, then increase the mass of the camera - simple. I wanted to test this idea and make a test video with and without extra mass on the camera. I was thinking - what could I attach to it? A 2 lb or 5 lb scuba weight came to my mind. Then it hit me: a water bottle. When do people use these little video cameras? To film their kids or something? If…

Lighter but strong cars, still dangerous

First, I think we should all be using smaller lighter cars. They get better gas mileage, they are better for the environment and maybe even reduce traffic? (ok, not sure about that last one - but it is possible). In Buzz Out Loud 918, they were discussing Toyota working on new car bodies built from sea-weed based plastics (from a wired article). One point that was brought is the comparison between old plastic bodies (the pontiac fiero comes to my mind) and these new plastics that should be much stronger. Well, here is the problem. Light strong bodied cars can be dangerous. Really? Yes…

Newton and small video cameras

Just to be clear, Newton probably didn't have a portable video camera. I do. I have one of these Flip Mino pocket cameras. Very nice. You can put it in your pocket. However, there is a problem with cameras like these (think of video from camera phones). The problem is the mass, it is too small. Video from a camera phone or small portable camera looks too jerky (unless you are careful). Sometimes it is jerky to the point that it makes me feel barfy. The reason this happens is that with a small mass, a force can cause a significant acceleration. Let me draw a picture (you know I like…