## How high does Doodle Jump?

Posted: August 14, 2014 in Uncategorized
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I was playing a new update of Doodle Jump on my iPhone this morning and I suddenly thought it would make a pretty cool lesson on motion and it could actually apply to both GCSE and AS Physics, depending how you phrase your questions.

The idea is to find out how high the little alien in Doodle Jump actually jumps. There is no reference in the game to suggest what scale the screen has, so I used Vernier Video Physics and arbitratily set the distance between the block on which the alien was jumping (see video below) and the last but one block above the creature to be 10m.

I then tracked the position of the alien for one jump and the analysis of the velocity graph shows the gradient is not right, i.e. g is not close enough to 10m/s2.

So, I went back and changed the scale to be 4.5m between the two blocks mentioned above. That seemed to have done the

trick, as the gradient of the velocity – time graph in the video below is about 10m/s2.

If you look back at the Displacement – Time graph for the vertical axis, you can now see that the little alien jumps to a height of about 2.3m. That is quite something for a little fella like him.

Obviously, we are assuming the alien is jumping near the surface of the earth, or at least a planet with the same g.

Last week I finally got round doing something I had wanted to do with my Yr11 classes for a long time. We acted a Displacement – Time graph. This might not sound amazing to you and I have done a similar activity in the past, but this time the difference was that my learners could actually check their outcomes very quickly and without having to guess if their movements reflected the D-T graph faithfully, as they could use what I think is one of the best iPhone/iPad App for Physics, the Vernier Video Physics app!

Indeed, we could have used cameras to record the videos and upload the videos on our laptops to use with Tracker, but the versatility of an iPad and the simplicity of the Vernier Video Physics app made things very easy and intuitive.

So, what’s this activity about? Well, the learners split into groups of 3-4 and analyse the graph below.

Then, they organise themselves to act the graph. So, one person will walk along a straight line to mimic the graph, whilst the others in the group could help signposting important parts of the graph, as well as keeping the time.

You can see how the Vernier Video Physics app renders the video after tracking the object in each photogram. The images at the end are the displacement and velocity analysis after the tracking has been completed!

What do you think? Is this group representing the graph well?