Newton's Second Law: (Major Flaw in Lab)

[anth0ny]

Homework Statement

There is actually a major flaw in the procedure of this lab. (Hint: look at your answer to question 3). Can you find it? What could be done to correct this flaw? Are there any drawbacks to your proposed change in the procedure?

2. Question 3

What does the slope of the best fitting line on the Force-Acceleration graph represent.

The Attempt at a Solution

I would like to state the fact that friction during the lab was not taken account of however I do not understand how that ties into question number three... Is it because the graph is based on a theoretical value which is missing friction?

 

[Delphi51]

Welcome to PF, Anth0ny.
There isn't enough information to figure out your question.
What did you do in the lab? What measurements did you make, what graph did you draw, what did it look like?

 

[anth0ny]

Hey,

Thank you :) In the lab we set up a cart with a brick on top and then tied a piece of string to one end and let it fall by placing a certain weight on the other end. Ticker tape was used to record six points a second.

The first half from the right is my first distance, then there is a gap which I measured the time for and then finally the second half closest to the left is the second distance. Both distances are equal to 0.1 seconds while the gap is a certain amount of time in this case (3/6) x 0.1 seconds. I converted the cm into m. Finally I used that data to calculate both the force and acceleration:

Finally I graphed it using excel:

Thank you for helping me out by the way!

,
Anthony

 

[Delphi51]

Okay, I have seen this experiment many times. I trust you had a pulley on the string to reduce friction.

It sounds like you made only two measurements - the distance traveled in 0.1 seconds in two places on the tape. Curious, you say the tape records 6 points per second, so they are 1/6 second or about 0.16 seconds apart - so how could you measure for 0.1 second?
What could you graph with only two measurements? Just 2 dots on your graph? Also no mention of how you calculated the acceleration or the force.

The first post mentions a force vs acceleration graph.
Did you repeat the experiment with different hanging masses so you have accelerations for various applied forces? That is the only way you could make such a graph.