The purpose of this lab is to use the principles of rotational equilibrium to determine the mass of a single paperclip.

In this experiment, the 5 washers are providing a counterclockwise (ccw) torque which has a magnitude that remains constant. By changing both the number of balancing clips and their position relative to the knifeedge, you will be generating 10 data points that have equivalent clockwise (cw) torques.
VI. Through a combination of moving the balancing clip hanger and varying the number of clips, find ten (10) different locations that balance the five washers. Fill in the following chart as you proceed through the lab.
Note that you are NOT to include the hanging clips in your totals since they cancel each other out. Both the 5washers and each collection of paper clips are suspended by a paper cliphanger.

# of clips

Position of clips

Moment arm of clips

Reciprocal of moment arm

TRIAL 
N 

L

1 / L



(cm)

(m)

(1/m)

1





2





3





4





5





6





7





8





9





10





Using EXCEL, plot a graph of # clips vs 1/moment arm. Save your file as lastnamelastnametorque to the computer's thaw space. Before printing your graph, be sure that the print area includes all of the data table and the graph.
Use the following format for your EXCEL spreadsheet. Part II Procedure:
Remove the washers and offset the knifeedge 6cm from its location in Step I. Then use paper clips to bring your beam back into equilibrium. Record the new knifeedge position, number of paper clips (counting the hanger) and the position of the clips in the blanks below. Then calculate the moment arms for the meter stick and clips.

Refer to the following information for the next five questions.

Refer to the following information for the next two questions.
Conclusion #1: We will now use linear regression techniques to determine the mass of a single paper clip. To begin, we need to write the theoretical equation that models the data you graphed.
Recall from Part I of your lab that the paper clips provided the clockwise (cw) torque and the washers provided the balancing counterclockwise (ccw) torque to produce rotational equilibrium. Mathematically we can write this relationship as
Since your EXCEL graph is titled N vs (1/L) you need to solve the equation given above for the number of clips, N, so that this equations parallels the form of the generic equation of a line: y = mx + b.
What was the numerical slope of your trend line in EXCEL? 
Refer to the following information for the next four questions.
Conclusion #2: We will now use your data from Part II to obtain a second value for the mass of a single paper clip.
In this part of your lab the weight of the meter stick provided the clockwise (cw) torque and the paper clips provided the balancing counterclockwise (ccw) torque, so our initial equation would be
Note that N must include the hanging clip since the meter stick's center of gravity does not have a corresponding clip to cancel out its weight.

After submitting your lab results online, turn in one copy of your EXCEL data sheet and graph (displaying the trend line's equation and R
^{2} value). Make sure that the names of your group members have been filled in.