Monday 27 October 2014

Motion Sensors to work out Distance Speed Graphs

Using the Motion sensor here we can do a series of experiments simultaneously to record the Distance, Velocity and acceleration of the cart as it moves down the track.

Here we are using a Lego trolley with a screen at the back to reflected the ultrasound signal.

The cart can be loaded with different masses.
Here are some distance time graphs to show four different runs at four different heights.

As the trolley moves down the track its velocity increases until it crashes at the end and the velocity drops sharply to zero.

1 was the shallowest
3 was the steepest.


Wednesday 22 October 2014

Hot and Cold Water Diffusion


A classic way of showing diffusion is to add a small purple crystal to water and let it diffuse. By having two set ups one with hot water at around 80C and the other at 15C ( straight from the cold tap ) an idea is given on how temperature effects the rate of diffusion.

Tuesday 14 October 2014

Using a Colorimeter to follow the rate of a reaction

With a new bit of kit I have been looking at the rate of reaction of an old favourite, HCl and Sodium Thiosulphate. This system has many advantages over the usual practical, not the least being that the reaction takes place in asealed cuvette so there is no smell and the amounts of substances are very reduced.
The Pasco software (in this case Saparkvue) makes recording this a breeze, creates the tables and graphs so that the data can the analysed easily.
A small amount of the chemicals are used ( approximately 6ml per experiment. The cuvette is filled with the required mixture and the placed in the calorimeter. This calorimeter records all the wavelengths at the same time so I don't have to worry about selecting the correct one, but simply the best one at the end of the experiment.

Before the experiment is started it is necessary to calibrate the colorimeter  but a cuvette of pure water, then it is simply a task of placing the solution to be examined in the cuvette and clicking start
The results can then be exported to word with any analysis. This system seems so much better value for money than other systems I have used.

Tuesday 7 October 2014

Calculating the Specific Heat Capacity of Aluminium using Dataloging


I took a 1kg Mass of Aluminium and heated with an Immersion Heater for 10 minutes. After heating I left the Mass with the hrater in but switched off for another 3 minutes until the temperature settled.

The Al mass was insulated to prevent too much heat from escaping.
I used a PASCO  temperature probe to record the temperature change.

The blue line represented the temperature and the red line the voltage.
Temp start 20.7
Temp end  41.3
Voltage 10.1V Current 3.84A Time 600 secs
Mass 1 Kg

From this data we can work out the specific Heat Capacity of Aluminium

Energy in = Volts x Amps x Time

Energy in = 10.1.x 3.84 x 600 = 23270.3 Joules

SHC Al =  Energy In / Mass x Change in temp

SHC AL = 23270.3 / 1 x 21.6 = 1077.8 J/K

Its a bit high rather than the theoretical value of 913 but then the insulationwasn't as good as it could be.



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