- Activity 1 Today You Will Be Designing Your Own Experiment You Will Test The Period Of A Pendulum And How It Is Affec 1 (88.02 KiB) Viewed 15 times
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- Activity 1 Today You Will Be Designing Your Own Experiment You Will Test The Period Of A Pendulum And How It Is Affec 3 (64.68 KiB) Viewed 15 times
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Activity #1: Today you will be designing your own experiment. You will test the period of a pendulum and how it is affected by changing the mass and then separately by changing the length. Vary each of these variables over at least five different values and measure the resulting period. To get your minds thinking about how to design your experiment, first consider the following statements before beginning the experiment. a. What procedure you will you use to investigate each of the independent variables, i.e. pendulum length and mass b. Predict how you think the independent variable (pendulum length and mass) will affect the dependent variable (Period of the pendulum). c. Be sure to diagram each experiment and illustrate how you changed the independent variables of length and mass. Answer the following questions to guide your experiment preparations. 1. What techniques will you use to obtain a reliable and accurate measurement of the period? Is it best to base your measurement on one period? Five? Thirty? Why? Swing the pendulum 4 calculate 20 oscillations, then = by total time To eliminate enor we should do this at least 5 times more times (= more accurate) passage through an extreme position. For each of the investigations, answer the following questions (4 & 5): 2. What variable(s) was (were) held constant? Which one(s) was (were) changed? Over what range did you vary the variable(s)? You can use the space below to make notes on these items. Gravitational acceleration (4) 4 mass of the pendolum will be Length (1) of pendolum will change range (20m-10cm) constan
To Begin the experiment, you will need to set up a pendulum in your home. You might follow a olan similar to that outlined below, but each pendulum may be different, depending on how you set it up and what materials you have. a. First, find a location where you can swing a roughly one meter pendulum freely without hurting anyone or damaging anything. b. Once you have your location, you will need to create a "pendulum stand". This could be the back of a chair. A door knob, or any place you could tie a string and have the string swing freely without touching the floor. c. Measure out about 1 meter of string d. Affix one end of the string to the pendulum stand. Tie it to a door knob, tape it to a chair, etc. e. Tie a small ball at the other end of the string, such that it can swing freely still. f. Pull the ball back to about a 20 degree angle and measure the period of the pendulum with a stopwatch or cell phone timer. g. Chane the independent variable and repeat step F above. h. Make a data table and insert it into the lab, listing all values of the dependent and independent variables. i. Repeat the experiment above for the other independent variable. j. When you try different masses, you may not be able to measure mass easily, but you should describe how you estimate the mass. You will need to find household objects that you can easily tie to the string, but will NOT break the string from being too heavy. 3. Based on your data, determine the relationship between the investigated variable and the period of the system. Write a statement in words summarizing the effect (or lack of effect) of the variable on the period. In order to answer this question fully, you will need to graph Period of Pendulum (y axis) vs. Independent Variable (x axis) in a spreadsheet software (Exel, Google Sheets). Include that spreadsheet graph in the box below, along with the description. тале As we increase the length of the pendulam; the time period will change, The value of I does not depend on mass, so if we replace the bob, the time not change 4. Repeat # 3 for the other independent variable, and include the graph and description in the period will space below. In case of independent variable, the value of I remains the same. 5. Which of the investigated variables had the greatest effect on the period? Is this what you expected? Did any variable(s) have no effect? length (e) has greater effect, yes it was expected. (m) has no effect on time period.
Activity #2: It can be shown (for example, see your textbook) that for a general pendulum system, the period can be described as: T = 2*π *[1/(m*g*d)]. Where: -I is the moment of inertia of the pendulum (About an axis through its point of support and perpendicular to its plane of swing) -m is the mass of the pendulum -d is the distance between the pivot point and the center of mass of the pendulum. Note: Some common expressions of I are given in the table in your textbook. 6. Using this theoretical expression, what is the period of a simple pendulum? Elaborate on which expression you chose to use for 1. 1 = M₂L²² ₁ R=L & L = length of pendulum T=2^pix surt (MxL² / Magal) + 7 = 2x pix sert (L/g) 7. Does this theoretical expression agree with your results/graphs in Activity #1? According to the theoretical expression above, SHOULD your data show a change in the period, or not? Activity #3: 8. Make a pendulum out of a meter stick, pipe or other solid object, not a mass on a string, by holding one end and letting the other end swing like the pendulums from Activity #1. While it is swinging, determine the period of its motion. Write out a description of the object you used and the period you calculated. I used a rod (length d) bong it by its end. (1) moment of inertia is calculated as 1 = md ² / 3 aka T = 2*11 (mxd3 / 3 xmec A T=2x^(d/3g)/2 9. How is the pendulum you just created (physical pendulum) similar to or different than those in Activity #1 (simple pendulum)? #8 can be reduced down to an expression of a simple pendulum. suspension Physical pendulum does not need a string for while a simple pendulum needs a string for support
10. Does your data for the meter sticks agree with the theoretical expression for T given above? Which expression for moment of inertia did you use (you may have to estimate this)? Determine a value for the acceleration due to gravity based on the periods of your physical pendulum in this activity.