Session 9 - Bending Investigation

Session 9 - Bending Investigation

Results

Table to show how much the ruler bends when we change the distance at which the force is applied

Graph to show how much the ruler bends when we change the distance at which the force is applied

Conclusion

As we can see in the table and the graph; the further away we put the plasticine ball (weight), the greater the bending will be.  To understand this we must understand the next equation:

Moment = force · distance

Force will always be the same in the equation (it will be constant) and if we multiply it to a number each time bigger, so will be its result. Therefore, as we increase the distance, then the moment will increase too. That’s why the bending is greater as we increase the distance from which we apply the force.

However, observing the graph we can see that the relation between the distance and the bending isn’t directly proportional as it is a curved line instead of a straight line. In our hypothesis we predicted that if we double the distance, the bending would double too. However, we can see that as the distance increases, the bending increases even more than we expected. This might be because we could have made some errors in the procedure and that's the reason why the line isn’t straight and both variables are directly proportional, as we predicted in our hypothesis.

Evaluation

There are several things that could have gone wrong whilst we carried out the experiment that could have affected our results. Although, the results are approximately the ones we expected in our hypothesis, they were used by us to observe the general tendency. The graph above should have shown a directly proportional relationship between our two variables, however we can observe an exponential curve, this suggests something must have gone wrong during our experiments. These are the main factors that could have affected our results and made them imprecise:

Firstly, the balance with which we weighed the mass (plasticine) could have not been calibrated and therefore the results are being manipulated as they are not the ones they should be. This is a systematic error as it always gives a result that is incorrect by the same amount. For the next time we should make sure the balance is calibrated and works correctly by trying to weigh the same thing with another balance and check that both results are the same.

Furthermore, as we held the ruler with which we saw how much the first one bended with the hand, it moved, and we couldn’t see exactly how much it bended, so, for the next time we should put it on top of a chair so it stays straight and on top of a stable material, and therefore measure it accurately and correctly.

Also, we might have not put the weight exactly at the right length, as it was quite big and so we couldn’t  measure it to. This could be considered as a random error. Next time we do the experiment, we should tie the wight with a rope to the exact position we want it to be.

The last thing that could have gone wrong whilst we carried out our experiment was the fact that the ruler could have moved from its original place as we were holding it there with our hands. The ruler that bends should have on top o the table 5cm and with the rest sticking out, but as we were holding it in place with our hands, this distance might have changed slightly and therefore changed our results. As a solution to this, next time we could use a weight or cellatape on top of the origin of the ruler to keep it in place and avoid these kind of problem

Bibliography

• BBC - KS3 Bitesize Science - Forces : Revision, Page 8. (2016). Bbc.co.uk. Retrieved 8 March 2016, from http://www.bbc.co.uk/bitesize/ks3/science/energy_electricity_forces/forces/revision/8/
• schoolphysics ::Welcome::. (2016). Schoolphysics.co.uk. Retrieved 9 March 2016, from http://www.schoolphysics.co.uk/age11-14/Mechanics/Statics/text/Balancing_/index.html