Errors in this experimental physics lab

[Lolagoeslala]

Homework Statement

Errors that might arise through this experiment:
A puck upon a air table which makes certain dots with a specific length in between each of them for a 50 g mass and a 150 g mass, we need to find the acceleration, which i did and the coefficient of the friction that they both might face. However the friction r not the same.. when they r supposed to be due to my teacher. Anyhow.. what might be the errors in this lab?

The Attempt at a Solution

1) gravity might vary from places
2) ruler lengths might vary
3) mass of string not taken in
4) friction of string and pulley ignored
5) uncertainty of masses
6)the unleveled surface
7)air resistance
8) changes in the temperature or the humidity.

 

[CWatters]

Somehow I doubt gravity is varying enough to be detected :-)

How much did the coefficient of friction change?

What happens to the puck if you put a really heavy weight on it such as 10kg on it?

 

[Lolagoeslala]

Somehow I doubt gravity is varying enough to be detected :-)

How much did the coefficient of friction change?

What happens to the puck if you put a really heavy weight on it such as 10kg on it?

the coefficient of friction for 50 g was 0.003 and for 100 g 0.008