Investigation into cantilever structures

Preliminary work

I set up the apparatus as shown in the diagram. Leaving 75cm hanging over the edge of the desk and placed the Newton meter at 90cm as the deflection will be easier to record. I then applied a weight to the Newton meter and recorded the deflection.

I stopped at 8N as the stress on the ruler was high and it might snap and be unsafe if any more strain was put on it. I also chose to increase the weight by 1N each time as it gives more accurate results as there are more values to compare to each other and using integers as the weight makes it easier to record results.

Prediction

Increasing the load will increase the deflection. Therefore doubling the load will double the deflection. This would mean that the load is directly proportional to the deflection. Assuming the ruler is elastic and that the pivot doesn’t change. This is because

Moment = perpendicular distance*force

As the perpendicular distance is a constant thorough the experiment the doubling of the load will double the moment which will cause the cantilever to deflect downwards.

Apparatus