What Causes the Difference Between Calculated and Experimental Acceleration?

[Ninjarzz]

Homework Statement

So we did a lab this week in my physics class.

We had a car on a horizontal table, that was attached to a string with weights (The weights were over the edge of the table.) We then calculated the experimental acceleration and the calculated acceleration. These numbers were different.

My teacher asked us "What was causing the difference between the calculated acceleration and experimental acceleration..."
He also mentioned something to do with Newton's laws.

Do you know the answer/Can help me out?

HUMAN ERROR IS NOT THE ANSWER...And the the time was taken by a electronic device.

Homework Equations

g = 9.8 m/s

The Attempt at a Solution

I really don't know how to start! what's causing the difference!

 

[unscientific]

Friction, human reaction time. F = d(mv)/dt

Since friction affects net force, reaction affects time, one wouldn't expect to get the exact answer..

 

[Ninjarzz]

Friction, human reaction time. F = d(mv)/dt

Since friction affects net force, reaction affects time, one wouldn't expect to get the exact answer..

I'm not really sure what you mean by human reaction time?

Elaborate? like ... the time that i calculated forit to go? because it was takeen by a stop watch

 

[unscientific]

ok, human has a reaction time of about 0.19s. Which means you could have pressed the time too late, which means the time u measure is more than the the theoretically calculated time.