Educational app for graphing position, velocity, and accel

[bcrowell]

I thought other physics teachers here might be interested in this browser-based educational application I wrote: http://www.lightandmatter.com/velocity/ . As you move the mouse up and down, it graphs its position, velocity, and acceleration. In the past I've had some classroom exercises that used this sort of thing, but I did them using ultrasound sensors. The ultrasound setup was flaky and time-consuming to set up during lecture, so I think this may work better. Here are a couple of sample activities:

task 1

Your goal is to produce an x-t graph that looks like a staircase going down and to the right.

Discuss with your group (a) how you would need to move the mouse in order to accomplish this, and (b) how the v-t graph would look.

Now try it, and compare with your prediction. If your prediction was wrong, discuss why.

task 2

Imagine -- but *don't do it yet* -- that you repeatedly wiggle the mouse up and down, doing it fast but smoothly. (You may actually find it physically smoother to move the mouse rapidly in a circle; the horizontal part of the motion will be ignored.)

As a group, predict what the x-t, v-t, and a-t graphs would look like, then test your prediction.

 

[Greg Bernhardt]

Nice work Ben! Posted the link on the PF twitter page!

 

[martane]

As a fellow physics teacher, I must say that this browser-based educational application looks really interesting and useful for teaching about motion graphs. I have also used ultrasound sensors in the past for similar exercises, but I agree that they can be quite finicky and time-consuming to set up.

For task 1, I would suggest starting with the mouse at a high position and gradually moving it down in a stair-step pattern, pausing briefly at each "step" to create a distinct change in position. This should result in a downward sloping x-t graph with distinct horizontal sections. As for the v-t graph, I would predict that it would have a series of downward spikes, corresponding to the pauses in the mouse's motion.

For task 2, I would predict that the x-t graph would have a series of smooth, curved sections going up and down, with a gradual overall downward trend. The v-t graph would likely show a series of positive and negative peaks, corresponding to the upward and downward motion of the mouse. And the a-t graph would probably show a constant, alternating pattern of positive and negative values. However, I'm curious to see how accurate my predictions are and will definitely try this out with my students.

Thank you for sharing this great resource with us! I'm sure it will be a valuable tool for teaching about motion graphs.