# The Deflection of a Cantilever When Weights are Placed on It

his investigation is into the deflection of a cantilever when weights are placed on it. Input variables of this investigation I could study \ The input variables are: - ? Mass On the ruler ? Length of ruler(overhang) ? Thickness of ruler ? Material of ruler ? Position of weights on ruler The input variable I am going to choose is the mass on the ruler. Therefore the input variables I must keep the same are as follows: - ? Position of weights on ruler ? Length of ruler(overhang) ? Width of ruler ? Material of ruler The outcome variables I am going to measure is the effect of masses on the ruler from this I am going to measure the deflection of the ruler in cm. I learnt from my preliminary experiment what my ranges should be and how many results I would need to prove my prediction. Also I learned how to set up my apparatus and how big or small my overhang should be.
My prediction of this experiment My predictions for the outcome of this experiment are as follows, that the amount of deflection will be directly proportionate to the amount of masses applied. Also if you double the weight you double the deflection. My reasons for this are that the amount of pressure applied will push the ruler down this is due to the gravitational force, which is being applied. This will cause the ruler to bend and stretch due to its elasticity. "The momentum of a body does not change unless it is acted on by an external force" In my experiment the external force would be the weights which I was applying. "If the deflection was doubled then the deflection would also double" This is possible to see if u look at my graph. Method I am going to set my apparatus up as I have drawn on the diagram. The measurements I am going to use are Newton for the weights on the ruler and cm for the measurements of deflection on the ruler after weights have been applied. To keep accuracy I am going to use a setsquare to measure the deflection also I am going to always measure from the top part of the ruler to make it a fair test. The range which I am going to measure the investigation are as follows a range of 0-10 Newton for the weights which are to be applied and the overhang on the ruler is going to be 80 cm. I am going to repeat the experiment three times to prove reliability of my results. Apparatus Retort stand, clamp, ruler, weights, SetSquare and a desk clamp. Hazards in this investigation Care to be taken with the amount of weights on ruler not to snap it, care while handling weights not to drop them and cause injury etc. Sources of information I use information from the lesson and also information from my Physic book (Keith Johnson Physics for you). The Hutchinson encyclopaedia p762. Results -?? Weight (N) Amount of deflection (cm) Averages(cm) 0 0.0 0.0 0.0 0.0 1 1.6 1.5 1.7 1.6 2 3.1 3.1 3.2 3.1 3 4.9 4.7 4.8 4.8 4 6.2 6.2 6.3 6.2 5 7.8 7.8 7.9 7.8 6 9.5 9.4 9.4 9.4 7 10.9 10.9 10.9 10.9 8 12.4 12.5 12.5 12.5 9 14.0 14.0 14.0 14.0 10 15.5 15.5 15.5 15.5

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