## The Barbie Racer and more physics

18/11/2015Online videos can support the teaching and learning of physics achievement standards, writes Dr Simon Taylor.

To support the teaching and learning of NCEA Physics 2.1 and 3.1 achievement standards, I’ve put together two video clips.

**Graphing and discussing relationships between two variables**

This video discusses helpful tips on graphing and discussing non-linear relationships between variables in physics investigations, 2.1 (AS 91168) and 3.1 (AS 91521).

There are explanations of the different types of graphs and how they are transformed.

It’s an area where students can get stuck, initially with noticing the shape of the first graph, identifying the relationship between the two variables and then transforming the data to confirm the relationship.

Four different relationships are drawn and discussed i.e. square, square root, inverse and inverse square.

**The Barbie Racer**

The ‘Barbie Racer’ activity is a simple and fun physics practical investigation of the non-linear relationship between distance travelled of a Barbie toy car and the time taken for it to roll down a ramp.

The video features a discussion of the control of variables, techniques to increase accuracy, limits and the physics ideas.

This investigation could be used at both Level 2 and 3 Physics. One advantage of having the incline (ramp) with a gentle slope, is that the ratio between reaction time and run time will be as small as possible.

This investigation could be a good place to start when it comes to building student understanding of a physics relationship that is non-linear.

The distance of the rolling Barbie car (independent variable) is proportional to the time (dependent variable) squared.

It involves simple equipment: a stop watch use of a mobile phone, a tape measure, a ramp with a gentle slope and a toy car that rolls without pushing down the incline.

The Barbie car is the ultimate investigation vehicle: good looking, good rolling with long wheel-base and stability. Ken can ride too.

Students can initially work in teams setting up the investigation, discussing ideas and techniques to improve accuracy, and the physics ideas on why the Barbie racer rolls down an incline.

They can record the data, and then work independently to write up a report. The data gathered is usually reliable (if it’s repeated, similar results occur) and most students are able to measure three to four time trials and then average the data in a couple of lessons.

There are also many uncertainties to consider: error bars can be added, a line of best fit with error lines drawn, also limitations to the investigation and surprises in data to talk about.

The most important idea to remember is have fun and enjoy being together talking about physics!

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