Cantilever Deflection.

Variables/Factors

• The mass on the ruler – I am going to increase this, starting from 0.1kg, increasing it in steps of 0.1kg, up to 1.0kg.
• The deflection of the ruler – I am going to place certain amounts of masses on the ruler, and then I am going to measure the deflection of the ruler.
• The heaviest mass that I am going to place on the ruler – The heaviest mass that I am going to place on the ruler is 1.0kg, this is because if I place a heavier weight on to the ruler, it is most likely that the ruler will snap.
• These are the variables that I must keep the same.

1. Where I’m going to place the masses on to the ruler.
2. How I decide to place the ruler.
3. Where I decide to have the pivot.

• I am going to control the masses that I shall place on to the ruler.
• I am going to measure the deflection of the ruler, when various masses are placed on to it.  

Diagram

Method

I will set up the apparatus, as shown.

Then I will test it with masses on it over the range, that I describe in my variables.

Results  

Analysis

The graph shows that the mass on the ruler had an effect on the deflection of the ruler. You can also realise, by observing the graph, that if the mass on the ruler was increased from 0.2kg to 0.4kg, the ruler would deflect by double the amount that is placed on it, therefore it would deflect from, 10mm to 20mm. There is an upward trend, which shows us that as we increase the mass in proportion, the ruler will deflect in proportion. This trend is conclusive, as I had earlier predicted that, as the mass increases, the deflection of the ruler would increase and that the trend line would go through the origin. I expected this to occur, because I believed that if there was more mass on the ruler, then there would be more weight, therefore there would be a greater force acting down on the ruler, causing an unbalanced moment, thus causing the ruler to deflect. As I was aware of this scientific knowledge, it was obvious, that increasing the mass on the ruler would increase the deflection of the ruler.  

Evaluation

The experiment, gave very reliable results. This is because the results lied very close to the trend line on the graph. The reasons for this might include:

• There was only one person taking the measurements.
• The same ruler was used throughout the experiment.
• The masses were placed in a fixed position during the experiment.
• The pivot was in a fixed position during the experiment.
• The ruler was on its side throughout the experiment.
• A suitable range of masses were used for the experiment.