magnet is in Phy p34.
I've googled for many sample experiments for this "oil viscocity". And visited a lot of pages to see how the experiment can be done, what are the possible errors, and improvement methods..
These are some of the good answers that I found.
Oil Viscosity
Error
1. small air bubbles are formed on the marble/spheres/(any balls being used) which hindered the motion of the ball
2. two sets of reading not enough to draw a valid conclusion
3. human error in timing
4. marble may have not reached terminal velocity
Method of improvements
1. release the ball/marble just a few mm above the oil surface
2. take more readings and plot a graph
3. use light gate to trigger stopwatch/high speed camera with known time intervals/use video camera with slow motion replay
4. ensure the terminal velocity by increasing the release height/using long tube/measure velocity at two intervals to check terminal velocity reached.
I took three of the errors and method of improvement from october/november 2007 paper 32 question 2 marking scheme.
It is also about terminal velocity.
There are other general improvements that I've found in net...But, I dunno how to state a possible error for them.
1. marble released gently into the top of the solution and that it doesn't touch the side of the tube. Using a wider tube
2. Allow oil to stand for a while to let it settle removing all air bubbles.
but keep ur mind cool and calm in the paper to get new improvments in ur head at the right place and at the right time...............................
