Friction is a counter force, which works (acts) in the opposite direction as the object moves.
When an object is in rest the position (x, y and z co-ordinates) of that object in space is fixed at each instant.
When an object moves the position (x, y and z co-ordinates) of that object in space is different at each instant.
Accelaration is a calculated number (vector) which indicates the change in speed of an object at each instant. When in state 1 or state 2 the acceleration is zero. During state 3 the acceleration is not zero and the number is either positive or negative.
During state 3 the sum of all the forces that act on that object is non zero.
To demonstrate movement and force the displays shows the position of an object at 200 instances. Each instance is identified as an dot.
When the object is in rest the display only shows one dot.
When the object moves at each instance a new dot will be shown to identify the present position and the oldest position (dot) will be erased. The color of the object and the distance between the dots are an indication of the speed of the object. The total length is an indication of the average speed. The larger the distance between the dots the higher the speed.
In order to move the object the user has to apply force on the object. To do that the four arrows are used. The direction of the arrow selected identifies the direction of the force.
Two modes are involved: absolute and relative.
In the absolute mode when the RIGHT arrow is selected, then the object will recieve force to the right and the speed of the object will increase into the right direction. Each time when the LEFT arrow is selected the speed of the object will increase into the left direction. To bring the object back to its original state the LEFT arrow has to be selected the same number of times.
The same is true for the UP and DOWN arrow. When the UP arrow is selected a force is applied upwards and the object will move upwards. When the DOWN arrow is selected a force is applied downwards and the object will move downwards. To counter balance an upwards force the DOWN arrow has to be selected the same number of times.
The demonstration comes in two flavours:
When option 1 (without friction) is selected and the object moves then the object will move forever in the same direction, if no counter force is applied.
When option 2 (with friction) is selected and the object moves and no counter force is applied then the object will continue to move in the same direction, but not with the same speed. This is because the friction functions as a counter force in the opposite direction as the object moves.
The are two ways to demonstrate this:
In the relative mode when the RIGHT arrow is selected, then the object will recieve force forward and the speed of the object will increase into the forward direction. Each time when the LEFT arrow is selected the speed of the object will decrease. To stop the object the LEFT arrow has to be selected the same number of times.
The UP and DOWN arrow opperate perpendicular to the line of movement. When the UP arrow is selected a force is applied upwards based on the direction of movement. When the DOWN arrow is selected a force is applied downwards and the object will move downwards. To counter balance an upwards force the DOWN arrow has to be selected the same number of times.
The demonstration comes in two flavours:
When option 3 (without friction) is selected first use the right arrow 10 times to get speed and then the up arrow 20 times regulary.
This test simulates how an object behaves when constantly the same force is applied perpendicular to the direction of movement. In that case the object (for example the Earth) moves in a circle.
The accuracy is not very high. To increase the accuracy go first to the parameter selection display and change parameter 6 (# of iterartions per step) to 10 or (100) and then in order to see the difference repeat "exactly" the same what you have done previously.
Now perform the program: BASIC.EXE
From the Test Selection Display:
The following test is the "same" and includes friction.
Return to CHAPTER1.TXT
The program uses the following standard feature:
The movement of the body is by the four arrow keys as follows:
In order to simulate the different conditions the parameter selection display is used
From the Parameter Selection Display the following parameters can be changed:
0 = Select test display1 = Set standard parameters.
2 = Screen mode. Valid values are 7,8,9 and 12. Standard value = 9 3 = Wait time in second. Physical wait time between each simulation cycle. Standard value = 0.1 4 = Friction coefficient. Standard value is .05 0 means no friction
5 = Delta time in seconds between each calculation cycle. Standard value is 0.1
6 = # of iterations (Only applicable for test 3 and 4) Standard value = 1