0.9 Phy1060: motion -- displacement and vectors  (Page 2/13)

Listings

• Listing 1 . Using the Math.atan method.
• Listing 2 . The sum of two vectors.
• Listing 3 . The sum of four vectors.

Supplemental material

I recommend that you also study the other lessons in my extensive collection of online programming tutorials. You will find a consolidated index at www.DickBaldwin.com .

General background information

Bodies - not a reference to people

To begin with, physics textbooks often refer to something called bodies . By this, they are not referring to living bodies or the carcasses of once livingcreatures. Instead, they are referring to what people might ordinarily call objects.

For example, somewhere in this series of modules, we will discuss something call ed a free body diagram . A free body diagram can be drawn relative to any object, such as a child sitting motionless in a swing on the playgroundor a piano hanging on a rope.

Rest and motion

While nothing in the universe is truly motionless (at rest), some things around us such as buildings seem to be at rest, while other things such asplanes, trains, and busses appear to be in motion.

There is no such thing as absolute rest. However, two bodies moving together at the same rate (with reference to some third body) may be deemed to be at restrelative to one another.

Therefore, if you are standing motionless on the Earth, you are at rest relative to the Earth with reference to the Sun.

Kinematics and kinetics

The fundamental properties of motion are often referred to as kinematics . The relationships between motion and force are often referred to as kinetics . These are the topics that will be covered in this and the next several modules in this collection.

Displacement

If one body is moved with respect to another body, either one of them may be said to have had a displacement . Displacement, along with vector analysis will be the primary topics covered in this module.

Discussion and sample code

Creation of tactile graphics

The module titled Manual Creation of Tactile Graphics explained how to create tactile graphics from svg files that I will provide.

If you are going to have an assistant create tactile graphics for this module, you will need to download the file named Phy1060.zip , which contains the svg files for this module. Extract the svg files from the zip file and provide them to your assistant.

Also, if you are going to use tactile graphics, it probably won't be necessary for you to perform the graph board exercises. However, you shouldstill walk through the graph board exercises in your mind because I will often embed important physics concepts in the instructions for doing the graph boardexercises.

In each case where I am providing an svg file for the creation of tactile graphics, I will identify the name of the appropriate svg file and display animage of the contents of the file for the benefit of your assistant. As explained here , those images will be mirror images of the actual images so that your assistant can emboss the image from the back ofthe paper and you can explore it from the front.