4.2 Acceleration due to gravity lab error

[jakeginobi]

Homework Statement

My best fit-line for my average velocity time graph doesn't seem to start at 0 m/s. I have no idea how to explain this in my conclusion - http://imgur.com/zniGGkw. This lab was conducted by using a recording timer, and a mass. We started the recording timer first, then let go of the mass then stopped the timer once it reached the floor.

Homework Equations

acceleration due to gravity = -9.80 m/s^2

The Attempt at a Solution

I know it couldn't be air resistance in the beginning

 

[andrevdh]

I assume the time is for the mass to go from the top to the bottom and that the total it falled was kept the same each time? How did you calculate the average velocity?

 

[jakeginobi]

Each time interval, I selected the average velocity divided 0.050s; for instance at the 7th interval my individual displacement was 0.1689 (m) [downwards], and divided it by 0.050s to find the average velocity

 

[andrevdh]

It seems you are looking at the motion of the falling object over short time periods, 0.05 s. During such a short time period the object would not be stationary, even at the start. That is it would be approximately 10 x 0.05 = 0.5 m/s