Happy g day

Actually, it should be called Happy “Magnitude of the local Earth gravitational field” day. You know, 9.8 N/kg on September 8 (9/8). Get it? Well, the idea was for the physics students and faculty to build some stuff to do outside – projectile motion type stuff. Well, we had the idea a while ago and…

Physics 2 refresher

So, I hear you are starting your second semester of physics. One of the cool things about physics is that the second semester still uses stuff from the first semester. Maybe you forgot some of that stuff, so here are the bare essentials you will need to get by (this is assuming you are in…

Basics: The electric field

Suppose I take a 1 kg ball and hold it near the surface of the Earth. What would be the gravitational force the Earth exerts on this ball? And I could say “g” is: The magnitude of this force would then be 9.8 Newtons. And, if I replaced the ball with a 10 kg ball,…

Basics: The Electrostatic Interaction

Pre Reqs: vectors, forces This is typically the first topic in the second semester of introductory physics – the interaction between objects with electric charge. There are 4 fundamental forces that physics typically looks at: Gravity – an interaction between objects with mass – wow, I don’t have a post on the universal law of…

VCalc: Me Likie

Do you have an iPhone? I have an iPod Touch. Do you use vectors? Do you think RPN calculators are the bomb? Here is a RPN calculator for the iPhone that supports vector notation. VCalc by Silicon Prairie Ventures Inc. Oh – it is free. Here is a screen shot. I played with it some,…

How do you represent vectors?

Recently, I was talking about vectors. At that time, I had to stop and recall how I had been representing vectors. Ideally, I should stick with the same notation I used in Basics: Vectors and Vector Addition. But let me go over the different ways you could represent a vector. Graphical Maybe this is too…

An example of two collisions

Suppose you want to move an empty paper clip box by shooting it with a toy dart gun. Why would you want to do this? Don’t worry about that – this is my example and I am sticking with it. Should you shoot a dart that sticks to the box or should you shoot one…

Average Speed Argument

My dad and I had a disagreement. We were driving back from a trip and he let me take over the wheel for a while. His complaint was that I was driving too slow and it was driving him crazy. For me, I thought I was driving fast. My typical behavior is to drive 3…

Basics: Forces and the momentum principle

**Pre reqs:** [Free Body Diagrams](http://scienceblogs.com/dotphysics/2008/09/basics-free-body-diagrams.php), [Force](http://scienceblogs.com/dotphysics/2008/09/basics-what-is-a-force.php) The time has come to look at things that are NOT in equilibrium. The most basic question to ask yourself is: *”What do forces do to an object”*? Aristotle would say that forces make things move. Constant forces make things move constantly. Actually, Aristotle said there were two types…

Basics: Free Body Diagrams

**Pre Reqs:** [Intro to Forces](http://scienceblogs.com/dotphysics/2008/09/basics-what-is-a-force.php), [Vectors](http://scienceblogs.com/dotphysics/2008/09/basics-vectors-and-vector-addition.php) Hopefully now you have an idea of what a force is and what it isn’t. What do you do with them? The useful thing to do with forces is to determine the total force acting on an object. At the beginning of the introductory physics course, you will likely…