OBJECTIVES

In this activity you will learn how to:

$$ Create $3$D box objects

$$ Update the position of an object iteratively $($repeatedly$)$ to animate its motion

$$ Update the momentum and position of an object iteratively $($repeatedly$)$ to predict its motion

TIME

You should plan to finish this activity in $50$ minutes or less.

I. Setup statements

In this task, we are going to use VPython to model a moving cart on a $2\mathrm{.}0$ m track.

$1.$ In a browser, go to the webpage www$.$glowscript.org to get to the Glowscript home page.

$2.$ In the right hand corner click $$Sign In$$ and login using your existing Google account from Lab $1.$

$3.$ You are now on the Glowscript program development page where you can either run programs that you have previously

written or create new programs. We want to click on the $$Create New Program$.$

$4.$ In the pop$-$up display give the program the name $$Cart$$

a$.$ Creating objects

$5.$ We use a white box to represent the track. Type the following command and run the program.

track $=$ box$($pos$=$vector$(0,-\mathrm{.}05,0),$ size$=$vector $(2\mathrm{.}0,0\mathrm{.}05,\mathrm{.}10),$ color$=$color.white$)$

$6.$ We will now use a red box whose center is at the origin to represent a moving cart located at the origin. Type the following

command and run the program.

cart$=$box$($pos$=$vector$(0,0,0),$ size$=$vector$(0\mathrm{.}1,0\mathrm{.}05,0\mathrm{.}06),$ color$=$color.red$)$

Test Your Knowledge

Reposition the cart so its left end is aligned with the left end of the track.

Run the program and make are sure it is working.

b$.$ Initial conditions

To model the motion of an object over time, we need to know the value of two vector:

$$ initial position; and

$$ initial velocity.

You have already given the cart an initial position. Now you need to give it an initial velocity, velcart. If you push the cart with your

hand, the initial velocity is the velocity of the cart just after it leaves your hand.

$7.$ Give the cart a velocity of $0\mathrm{.}5$ m$/$s in the $+$x direction by adding the following command

velcart $=$ vector$(0\mathrm{.}50,0,0)$ #sets the carts velocity at $0\mathrm{.}5$ m$/$s in the $+$x direction