Balance of a metal rod problem.

[jim_boob]

1. Homework Statement
I am trying to determine the limitations to my experiment and thus how to improve them.
The experiment's objective is to determine the mass of a metal rod.
The rod is balanced every time another 1kg is added onto the end of the rod.
This means that the rod cannot be touching the clamp. (it has to be 'hovering' in between the jaws of the clamp)
A ruler with a precision of (+-1mm) was used
Ultimately, as the mass on the end increases, the distance (x) will decrease.
A graph was then plotted of (m), mass on the end of the rod against (1/x), 1/the distance between the pivot and the hook.


2. Homework Equations
Moment = Force x distance perpendicular to the line of action of the force
The linear cartesian equation: (y = mx + c) is equivalent to (m = MP(1/x) - M)
where m is the mass hanging on the end of the metal rod, M is the mass of the rod, P is a constant and x is the length from the pivot to the hook (where the mass is hanging).

Any ideas of the limitations and thus the improvements that could be made to this experiment? Thanks in advance.

 

[Valerie Park]

3. The Attempt at a Solution The limitations of this experiment include:1. The precision of the ruler used; (+-1mm) as this could lead to errors in the measurements taken. This could be improved by using a ruler with greater precision (e.g. +-0.1mm). 2. The accuracy of the balance used; if the balance is inaccurate then the results will be affected. This could be improved by using a more accurate balance. 3. The consistency of the mass added onto the end of the rod; if the masses are not consistent then this could affect the results. This could be improved by ensuring the masses being added onto the end of the rod are all of the same weight/mass. 4. The accuracy of the calculated value for the mass of the rod; if the calculated value is not accurate then this could affect the results. This could be improved by ensuring that the calculations are carried out accurately, double-checking any calculations and using better methods for calculating the mass of the rod.