Centripetal Motion Lab

1
Centripetal Motion Lab

• Notes on Lab Report

2
Outline

• Title Page
• Purpose
• Intro
• Procedure
• Data
• Analysis
• Conclusion

3
Purpose

• To verify the formula for centripetal motion
  using experimental values.
• F mv2

r
4
Introduction

• The introduction should explain all the ideas
  needed to understand the lab, such as
• What is centripetal force?
• What is the formula for centripetal force?
• Generally, how are you going to verify the
  formula in this lab?

5
Introduction

• What is centripetal force?
• The force that pulls an object in a circular path.

6
Introduction

• What is the formula for centripetal force?
• F mv2/r
• This can be solved for v to make

F centripetal force m mass of object v
velocity r radius of circular motion
7
Introduction

• Generally, how are you going to verify the
  formula in this lab?
• This equation can be tested by changing the F, r,
  and m and seeing if the effects on v make sense.

8
Introduction

• Generally, how are you going to verify the
  formula in this lab?
• For example, the F is on top of the fraction so
  if F increases so does V. So by increasing the
  centripetal force on the object, the velocity can
  be measured to see if it also increases. If it
  does, then the data supports the equation.

9
Introduction
If the data matches the trends described, then
the data supports the equation.
10
Introduction
Graphs can also help support the formula. Since
there is a square root in the formula, , the
graphs will be curved. The graphs should look
like the following
v
v F r
m
v
m
11
Introduction

• Finally, the formula should verify the force used
  in all three parts of the lab.

12
Introduction

• The force from the lab should equal the force
  from the formula, F mv2/r

13
Introduction

• The closer these values are, the better the lab
  supports the formula.

14
Procedure

• Copy the steps of the lab
• Write this section in steps
• Download the directions from the website
• Cut and paste them into your report

15
Data and Analysis

• Open the Lab Report Excel Spreadsheet file from
  the website
• Fill in your data for the mass, force, radius,
  and time
• The spreadsheet will automatically create your
  velocity, acceleration and force values.
• Your graphs will form in separate tabs at the
  bottom of the spreadsheet.

16
Data and Analysis

• To enter your mass, divide the little stopper
  mass by 1000.
• For Part 1 and 3 you used 1 stopper only so the
  mass is the same for all 6 trials
• For Part 2, multiply the of stoppers by the mass
  of 1 stopper to get the mass for each trial.

17
Data and Analysis

• To enter the Force values, divide the large
  stopper mass by 1000 and then multiply by 9.81.
• In Part 1 enter the stoppers times the mass of
  one stopper for each trial
• In Parts 2 and 3, you used 3 stoppers for the
  whole table so multiply the mass of one stopper
  by 3 and enter that in all of the cells.

18
Data and Analysis

• To enter radius values, for Parts 1 and 2 just
  enter the radius in meters, .2000m
• For Part 3, you have your own radius data. Just
  make sure you enter it in meters by dividing the
  cm values by 100.

19
Data and Analysis

• When you are done your data table will
  automatically make graphs
• You need to open the tabs at the bottom of the
  page
• Right click on any point
• Select Add Trendline

20
Data and Analysis

• Once in the trendline, select the Exponential
  graph
• Then select Options
• Select Show Equation
• Hit finish
• Repeat for all 3 graphs
• Print out the entire workbook

21
Conclusions

• The conclusion sums up the lab by describing how
  well the purpose was accomplished
• In a paragraph, explain how well the data and
  analysis support the equation F mv2/r.

22
Conclusions

• Did the values of the F, m and r cause the
  predicted changes in v?
• Did the graphs look like they were supposed to?
• Did the values of the Forcecolumn
  Fmacolumn?

23
Report

• Due next Thursday, Jan. 25th
• Typed
• Individually completed
• Data and analysis can be shared
• Introductions and conclusions must be unique no
  copying allowed