Newtonia31

NEWTON'S FLYING SPACE DONUTS (with Sprinkles)

The purpose of this applet is to allow you to explore aspects of Newton's ideas about forces and motion by pushing a donut (or bagel) around either in space with no friction or on a surface with friction (like a table top). We also can turn on and off gravity. If it is on, then the force of gravity (the weight of the donut) will pull the donut straight down (like would happen if you accidentally dropped a donut).

We will encourage you to explore differ aspects of this similation and will give you challenges to work on. Most of the challenges can be accomplished in many different ways. There may patterns in your solutions and these may tell us a lot about how the world around us works. Some of these may be surprising. For us to begin to see some of these patterns it will be very important for you to keep track of what you do and what you observe. At first it may seem easy to get started but unless you pay pretty careful attention, you may not see some pretty remarkable things (the sorts of patterns no one had understood, in a systemaic way, before Newton).

<Optional: You may want to think about these questions before you start working with the applet. These are the sorts of ideas that this applet will help us think about.>

This environment works in terms of shoves or quick bursts from a rocket. The arrow buttons tell use the direction of each push or pull on the donut. We think of these shoves or burst as forces (pushes or pulls) lasting for 1/10 of a second each time a button is pushed.

The graphs on the right tell us something about what these shoves or burst do to the motion of the donut (or bagel). If you push an arrow twice then two bursts of force are applied, each lasting 1/10th of a second. But for the applet to work you will first have to press the GO button. It wil turn black when you do this.

More directions on how to use the applet are given below. Before moving on to the challenges you should begin to explore how the environment works by leaving the sliders where they are and just shoving the donut around by pressing the N (up), S (down), W (left) or E (right) buttons. When you do this, what do you notice about how the donut moves? What happens to the graphs?

You should come up with three or more things you notice about the motion or the graphs before going on to the challenges. If you work with this applet with a partner, each of you should get a chance to do each challenge. Some challenges will require you to have different roles and work together. For each of these challenges you should remember to switch roles so that each of you gets a chance to do both roles before going on to the next challenge.

		This is the most important button. If it is not pressed (it will turn black when it is clicked on), then the simulation will not work. If you want to pause or stop the simulation press this button again and it will change back to a lighter color (but don't forget to press it again if you want to resume the activity).
		If you want to reset the simulation press the Start Over button. A little clock (see image) will start counting down from ten to zero. This is meant to give you time to move the donut around on the screen. If you don't need this time or you've finished moving the donut to where you want it, you can click on the number and it will stop and then disappear.
		These are the controls we'll use most. To start with we'll just focus on pressing the N (up), S (down), W (left) and E (right) buttons. Later we'll work with adding friction, adding gravity or changing the strength of the force (how hard the donut is pushed or pulled). How does the donut move when you press these buttons? Does it stay on the screen? Why do you think it works this way? Can you get the donut to stop? NOTE: If nothing is happening, then you probably forgot to press the GO button (see above).
		As you press the force buttons, you should notice both what happens to the motion of the donut and what happens to the graphs and especially to the velocity graph (the top graph). How many lines are there are the graph? How are these related to the motion of the donut. If the donut doesn't move at all where are the graphs? If you get the donut moving pretty fast, what happens to the graph? Can you get the graph lines to be flat? How? What is different about the motions when the lines move toward the top of the graph (toward the 5) versus the motions when the graphs move toward the bottom of the graph (toward the -5)?
		Challenge 01: [To start over, see above] Now you must press all four buttons at least once and yet have the donut fly diagonally up and to the right . Be careful to count how many times you press each direction button. Record these values and also record the values for your partner (if you have one, otherwise do two different ones yourself). Is there a pattern you notice? Can you think of a pattern that might be true for the values for all the flying donuts in class? Do we need to push all the buttons to get this kind of motion?
		Challenge 02: [Start over] See if you can predict what you'll need to do to get this diagonal motion but still press all four directions at least once. Record your values and answer the same questions as you did for Challenge 01.
		Challenge 03: [Start over] Start off getting a diagonal motion like what you did for Challenge 01. Without starting over, now try and get the donut to move only horizontally (like what is shown). There should be no upward (or downward) drift to the donut. For this challenge you DON'T need to keep track of the number of presses. Just try and get it to fly horizontally. Then be ready to describe what you and your partner tried at first, and then what ended up working.
		Challenge 04: [Start over] Now take what you noticed from Challenge 03 and see if you and your partner can each predict a combination of arrows that will results in (i) the diagonal motion and then (ii) a combination that will turn this diagonal motion into a horizontal motion. After you've written your predictions, then try the combinations. [If you can't predict, try a few until you see something that works and then write down how you did (i) and then how you got to do (ii).
		Challeges 05-07: [Start over for each of the following] (i) 05-Make and record the combinations you and your partner made to go in whatever directions you like but end up moving straight down (no drift in other directions). (ii) 06-Do the same but end up moving to the left (no drift). (iii) 07- And again, for straight up. If we listed possible combinations for each of these on the board, write how could you tell which ones would work for (i), (ii) or (iii)?
		Extra Challenge: Can you get the donut to move in something close to a circle? How did you do it? How might this be like what the sun does to keep the planets in orbit? <Some of you may have used the Catch-a-Planet applet. When you click the mouse, and hold it down, it acts like the sun. What does this mean in terms of the force of the sun (mouse location) on the planet(s)?>
		Next up, friction and gravity ...

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