1. Adjust your marble launcher to zero degrees. Place your marble launcher on a table or other flat surface or on the ground.

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1 Conceptual Physics Mrs. Mills Your Name: Group members: Lab: Marble Launcher Purpose: In this lab you will be using the marble launchers in order to examine the path of a projectile. You will be using the formulas discussed in lecture to estimate the initial speed of the marble as it is launched and also the distance the marble travels. You will compare theoretical range values to your lab results. Materials: 1 Marble Launcher 1 Marble 1 Meter Stick Carbon Paper White Paper Part 1: You are gathering information that is specific to your marble and marble launcher. For this reason, your group should use the same marble and marble launcher for the entire two day lab. You will not get a new marble if you lose the first unless you give me a dollar. Name of marble launcher: Number on sticker on marble: 1. Adjust your marble launcher to zero degrees. Place your marble launcher on a table or other flat surface or on the ground. 2. Mark the position of the launcher with tape in case it is accidentally bumped. 3. Measure the height of the muzzle opening with respect to the floor. ( Y i ). This must be in meters! Place this information in the Y i column in the first row of the table on the back of this page. 4. With the spring compression at 1 (first notch), launch the marble, noting where it hits the ground. Launch the marble by pressing on the trigger with a pen or similar object. Not your finger! 5. Now place carbon paper (shinny side down), with a piece of white paper underneath, on the floor centered on where the marble landed. Tape the white paper down with masking tape NOT THE CARBON PAPER. Fire the marble from compression 1 until you have 5 marks on the paper. If possible, catch the marble after it hits the ground once, so the marble does not leave additional marks on the floor. 6. The Range of your marble (X f ) is the distance IN METERS along the ground from the spot on the floor directly under where the marble is launched, to each of the carbon paper spots. Find all 5 range values and write them down here: 7. Go back to your seats in the classroom and finish steps 8-14.

2 8. Calculate the average range value and place it in the table under the Xaverage column. 9. The ball lands on the ground (y f ). What numerical value of height does ground represent? (Hint this is an easy question). Place your answer in the table. 10. The marble is launched with an initial horizontal speed and NO vertical speed. What should go in the V yi column? Place your answer in the table. 11. Use the following equation to find the time it took for the marble to fall. (a is 10m/s 2 of course). Place the time in the table. Show all work here: y f = y i + V yi t at The initial x-component of the velocity (Vx) is the same as the initial total velocity (Vi). Why is this true? 13. You can now use the equation for range(x) to find the value of initial velocity (Vx). Place the value for Vi in the table. Show all work here: x f = V x t 14. Show your teacher your work before going on. Teacher check: 15. Repeat Part 1 for spring compressions 3 and 5. Do the above calculations and fill in the table below. Table 1: Finding the initial velocity of the marble at 3 different compressions Yi (m) X average (m) Yf (m) Vyi (m/s) Time (s) Vi (m/s) Compression 1 Compression 3 Compression 5

3 Part 2: Main Lab Investigation Goal: Using the information and strategies learned in the first part of this lab, you will be required to hit a target with your marble launcher. You will be given a specific height and compression setting, and you must calculate where the marble will land. You will then place a target and carbon paper in this position. You will need to compare your predicted range to the actual range of the projectile. 1. Ask the teacher for your group s specific height and notch setting. Place this info in the table below. 2. Do a calculation #1 on the back of this page to predict the landing point of the projectile when fired under the conditions you were given. Place this value in the table below. Do not experiment until getting the next teacher check. Don t know how to start? First measure Yi and use it to calculate t. The use the correct Vi from part one (for your assigned compression) to calculate X f 3. Teacher Check (You must get this before going on, to show you made predictions before you experimented). 4. Using props as needed, set up your launcher to have the correct initial muzzle height, yi. 5. Place your carbon target at the predicted range. Launch the projectile from the notch given to you. 6. Measure the observed range and place in the table. 7. Calculate the percent difference using the formula: %difference = observed predicted predicted x100 Table 2: Predicted range of a marble vs. Observed Range Yi (m) Notch setting Predicted X (m) Observed X (m) % difference Extra Credit: Maximum range If your group finished the rest of the lab early, you may perform the following experiment. Using the angle adjustment on your launcher, you can change the initial launch angle. With the notch set at 3, find the angle that results in the maximum range. Hint: if your launch height and landing height are not the same, the angle will not be 45 so don t assume that s the answer! Describe the details of your experiment and write a conclusion. Fill in the table. Angle Range

4 Your Report: Here is a list of some of the questions that you must answer in the lab report: Why are the x and y directions treated with different formulas? Is anything the same for both the x and y directions? Were there trends in the data or just scatter (random differences)? What could have caused differences between your predicted range and the actual range of the projectile? Lab Report: Use the "Lab Report Rubric" to help you write your individual lab report. Introduction: You may use the purpose written on the lab. Procedures: Your procedures for part one should be a brief summary. You procedures for part two should be in detail since they may differ from other groups. Data Collection: I recommend that you rewrite your data so that it is neat and organized. Clearly label everything. Remember units and symbols! Graphs: There are no graphs for this lab. Answers and Calculations: Don t forget to explain why you used the formulas you did. Analysis: Remember to be specific. When talking about error analysis, use numbers. Conclusion: I am very interested in your suggestions for improvement or further study! Conventions: Please type if possible. Use spell check. Read it through before turning it in. Don t forget to include a cover page with your name and your partners names. Don t forget to include your original "Notes Page" stapled to the back of the lab.

5 Answer Sheet Part 1 Compression 1 Range 1 = Range 2 = Range 3 = Range 4 = Range 5 = Average Range: Initial velocity (show work): Height: Compression 3 Range 1 = Range 2 = Range 3 = Range 4 = Range 5 = Average Range: Initial velocity (show work): Height: Compression 5 Range 1 = Range 2 = Range 3 = Range 4 = Range 5 = Average Range: Initial velocity (show work): Height: Part 2 Height: Compression: Range calculated (show work): Measured Range Values: Range measured 1: Range measured 3: Range measured 5: Range measured 2: Range measured 4: AVERAGE RANGE: % Difference = measured calculated calculated x100 =

6 Conceptual Physics Mrs. Mills Name: Projectile Lab Answer Sheet 1. Prediction of landing point of projectile. Show all work. 2. In part one you found that if you know the initial height and range of a projectile fired horizontally, you can determine the initial velocity. What can be determined if you know the initial velocity and height of the projectile? 3. Why are the horizontal and vertical directions treated with different formulas? (Hint: think about the forces acting on the marble) 4. If you drop a bullet from the same height as one fired horizontally, which will land on the ground first and why? 5. What could have caused differences between your predicted range and the actual range of the projectile? Write a paragraph on the random and systematic errors that occurred during the lab. For each error, estimate how much it affected your results.