friction

Dot Physics

Tag archives for friction

More on turning and braking

I can’t let it go. There is more here to explore. First, I can’t believe that I looked at braking and then turning but not turning then braking. And what about braking while turning? I will model braking and then turning – but it won’t stop here. Consider a few motions. I could turn and…

Turn or go straight? Quick!

This is a classic problem. You are in a car heading straight towards a wall. Should you try to stop or should you try to turn to avoid the wall? Bonus question: what if the wall is not really wide so you don’t have to turn 90 degrees? Assumption: Let me assume that I can…

Experimental Rope Logarithms

Sue from Math Mama Writes… sent me an email about wrapping a rope around a pole. In that post, Sue thinks about rope looped around a post. When you wrap a rope around a post, the friction between the rope and the post can help you hold something (like a horse) that is much stronger…

Hat tip to Frank for sending me a link to this video: If you have never done a demo like this (without the motorcycle), you should. It really isn’t too difficult. Here is a video of my version: Inertial demo from Rhett Allain on Vimeo. So, the question is: is the motorcycle thing real or…

I ride my bike and mostly the wind makes me unhappy. On a very few days the wind is with me on the way to work and then changes so that it is with me again. But most days the wind is fairly constant. So, if the wind is constant then shouldn’t everything even out?…

Apolo Ohno Physics

It is winter Olympics time and time for physics. The event that I always gets me thinking about physics is short track speed skating. It is quite interesting to see these skaters turn and lean at such high angles. All it needs is a little sprinkling of physics for flavor. Check out this image of…

Simple Experiments with Friction

Now I get to do something with that force scale I built. I had a request some time ago to talk about friction. Friction is surprisingly complicated. When two surfaces rub against each other, why is there a friction force? The basic answer is that the stuff the two surfaces are made of (atoms) are…

Sport Science, Pulling and Friction

Forgive me for all the posts on ESPN’s Sport Science (example: Pulling and Power). I can’t help myself. In the short episode recently, Sport Science compared a football player pulling a sled with huge tires on it to a truck pulling stuff. I think their goal was to compare the power per kg from for…

I can pull more than 3000 POUNDS!

Note: This is part of my ongoing attack of ESPN’s show Sport Science. Really, I am continuing to look at the episode where they calculate a football player can produce 57,000 Watts by pulling some stuff. Wait…I don’t want to limit my stuff to Sport Science. I see this stuff all the time. The problem…

Lab: The Charge of an Electron

Not really. Here are the details (and some data) for the Millikan Oil Drop Experiment without the oil drop that I talked about previously (originally from The Physics Teacher – lucky you, it was a featured article so it should still be available (pdf)). The basic idea that Lowell McCann and Earl Blodgett from U…