Physics lab 3

Physics 1 Lab PHY 2221/2421 Section ____

Lab Title:__________________ Instructor:_________________

Name:____________________

Date:_____________________

Partners:__________________

2D Forces– Data Analysis

Data Analysis

The same force table experiment is conducted to determine an unknown mass. The experiment

setup is very similar to what you did in the classroom. The unknown mass is suspended on a string at

the angle 90.0° (see picture), while two known masses are suspended on the other two strings at

certain angles to balance the unknown one. The setup is shown in Figure 1.

(a) (b)

Figure 1: Force table experiment setup to determine an unknown mass. The side view (a) shows that one unknown mass and two known ones are suspended on strings to balance each other. In the top view (b), we can clearly read the directions of all forces.

The unknown mass remains fixed, while the two known masses and their angles are adjusted to

balance the unknown one. 10 sets of data were obtained and summarized in Table 1. Please use the

data to answer the questions.

Table 1: Force table experiment data.

Unknown mass angle (°) 90.0

Data Count 1 2 3 4 5 6 7 8 9 10

𝑭𝟏 magnitude (gram)

396 301 251 482 669 739 478 653 261 397

𝑭𝟏 angle (°) 292.7 324.1 299.9 303.0 330.1 319.4 288.5 288.5 288.5 299.5

𝑭𝟐 magnitude (gram)

356 566 481 385 676 596 280 220 446 391

𝑭𝟐 angle (°) 244.5 244.5 255.1 226.6 211.5 200.0 235.6 197.5 260.0 240.5

Question 1: (5 points)

Please only use data set 1, draw and label the 3 force vectors in the diagram below. Your drawing

does not have to be to the scale, but should roughly reflect the directions of the 3 forces.

Question 2: (5 points)

Please only use the data set 1 to calculate the unknown mass. Show your calculation procedures

and result below.

Question 3: (5 points)

Please use the 10 sets of data to calculate the unknown mass in Microsoft Excel. Record the result

for each individual data below. Please note that in Excel the trigonometry functions take angles in

radians. You need to convert angles given in degrees to radians first. The function =RADIANS()

converts degree to radian; the function =DEGREES() does the opposite.

Data count 1 2 3 4 5 6 7 8 9 10

Unknown mass (gram)

Question 4: (5 points)

Please process the 10 unknown mass results obtained in the previous question

Average Standard Deviation Standard error

Unknown mass (gram)

x

y

30

60 90

120

150

180

210

240 270

300

330

0

Question 5: (5 points)

Please determine the 95% confidence range for the “true” value of the unknown mass, show your

calculation procedures; then report the final result in the format “mean value ± 95% range”.

Question 6: (5 points)

The reference value of the unknown mass is 682 gram. Does the reference value fall in the 95%

confidence range of the mean value? What is the percent error?

Lab 3 Report – Presenting Data Table

Using tables is a convenient technique to organize, present and analyze information. When used correctly, tables can help the reader

quickly understand abstract concepts, trends, etc. hidden within the information. Usually, a data table is accompanied with some

description/explanation/discussion to build a narrative.

Please refer to the example on the next page.

Requirements:

In this report, please make one data table and write a paragraph to present the data and calculation results for the unknown mass. Please

think about how to organize the data in the table so that it is easy for readers to follow the data and easy for the important information to

stand out. The goal of the table and the paragraph is to address the question

• How well/poorly does the calculated unknown mass compare to the reference value?

Table

Item 0 points 2 points

Data relevancy Data in the table is inadequate to depict the calculation or to address the question.

Data in the table is adequate to depict the relevant calculation and to address the question. (What data should be included?)

Data organization Data is poorly organized. Data is organized for easy reading and to facilitate addressing the question. (What numbers do you want to compare?)

Table title and numbering

Table numbering and title are missing. Table is numbered and the title briefly summarizes the data.

Paragraph

Item 0 points 4 points

Table reference The paragraph does not cite data values in the table. The paragraph cites the data values in the table to address the question.

Logic (6 points) The narrative in the paragraph is not supported by the data in the table.

The narrative in the paragraph is supported by the data in the table.

Language Informal language with more than 3 errors and awkward content flow were used.

Formal language of natural content flow and with no errors were used

Don’t forget to attach a copy of this rubric to your lab report, otherwise 5 points will be marked down.

Sample table presentation

Table 1 below lists the average salary for some major programs for Lawrence Technological University (LTU) alumni. The data was obtained from the website www.payscale.com. Please note that this table does not include all major programs offered at LTU. Although the website claims that the data was updated on Aug 24, 2019, there is no way we can verify its reliability. The website gathered data through alumni self report; and the number of participating alumni seems very small (683); therefore the numbers cannot faithfully reflect the average salary landscape for LTU graduates. However, the numbers are in line with the national trend that art majors general earn less than engineering majors. For example, the alumni of Bachelor of Fine Arts earn the lowest average salary in the table, $49,500; meanwhile the two highest salaries, $100,600 and $110,960 go to two bachelor degrees of engineering. In addition, the table does reflect the well-known strength of LTU – its engineering programs; most of the higher average salary numbers belong to engineering related programs.

Table 1: Average Salary by major for Lawrence Technological University alumni

Major Average Salary ($)

Bachelor of Architecture 58,696

Bachelor of Arts 67,664

Bachelor of Business Administration 91,000

Bachelor of Engineering 94,972

Bachelor of Engineering Technology 110,960

Bachelor of Fine Arts 49,500

Bachelor of Science, Architecture 65,000

Bachelor of Science, Civil Engineering 67,619

Bachelor of Science, Electrical Engineering 100,622

Bachelor of Science, Mechanical Engineering 87,290

Bachelor of Technology 96,500

Content in the table is

referred to several times.

The table is numbered for easy reference; and

the title briefly summarizes the data content. Data is well organized in two

columns for easy read.

The paragraph describes the data source, and refers to the numbers, to stress its

merit despite its questionable reliability.