Recitation 1-6 Projectile Motion

Transcription

1 Preliminaries Recitation 1-6 Projectile Motion The Recorder is the youngest person at your table. The Recorder Should write down everyone s name on the worksheet and put your Table No. on the worksheet. Other You will turn these papers in at the end of the day so be neat. Task 1 Exit Speed Using the photogates Task 2 Time-of-Flight Using the photogate and time-of-flight accessory Table 1 Table 2 Table 3 Table 1 Table 2 Table 3 Table 4 Table 5 Table 6 Table 4 Table 5 Table 6 Table 7 Table 8 Table 9 Table 7 Table 8 Table 9 Task 3 Distances Equal Elevations Calculations Task 4 Distances Unequal Elevations Calculations 30 o 60 o 30 o 60 o 30 o 60 o 30 o 60 o 30 o 60 o 30 o 60 o Table 1 Table 2 Table 3 Table 1 Table 2 Table 3 Table 4 Table 5 Table 6 Table 4 Table 5 Table 6 Table 7 Table 8 Table 9 Table 7 Table 8 Table 9 1

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12 EF 157 Recitation Instructions Task 1: Determination of the exit speed. Equipment: Launcher, ball, tape measure, two photogates, timer. Procedure: 1. Set the launcher so that it is horizontal (i.e., 0 o ) 2. Measure the vertical distance (in cm) from the bottom edge of the launcher's bore to the floor (see diagram). Why the bottom? Record your answer on the worksheet. 3. Set the launcher on the medium (the middle) position. Load ball and fire. 4. Have three students mark where they think the ball landed (use small pieces of tape). 5. Repeat steps 3-4, two more times. There should be a total of nine marks. 6. Eyeball the location of the average mark. 7. Measure the horizontal distance (in cm) from the end of the launcher to the average mark. Record your answer on the worksheet. 8. Using one of the y-motion equations, calculate the theoretical time-of-flight. Record your answer on the worksheet. 9. Using one of the x-motion equations and the time value calculated in step eight; calculate the theoretical horizontal velocity. Record your answer on the worksheet. 10. Set the launcher on the medium (the middle) position and load the ball. 11. Activate the photogate timer. 12. Fire the ball and record the time on the worksheet. 13. Repeat steps two more times. You will have three measurements. 14. Measure the distance between the photogates. Using the average time measurement, calculate the exit speed. Record your answer on the worksheet. 15. Calculate the percentage error in the two determinations. Which one do you think is more accurate? Task 2: Time-of-Flight. Equipment: Launcher, ball, one photogate, timer, time-of-flight accessory. WARNING: The time-of-flight accessory is fragile. Do NOT step on it. Procedure: 1. Disconnect the second photogate from the timer. Connect the time-of-flight accessory to the timer. 2. Set the time-of-flight accessory on top of the average mark from Task 1, step Set the launcher on the medium position and load the ball. 4. Activate the photogate timer. 5. Fire the ball and record the time on the worksheet. 6. Repeat steps 3-5 two more times (three measurements total). 7. Set the launcher on low (the first) position and load the ball. 8. Fire the ball once and observe where it lands (you may have to repeat to get a good estimate). 9. Move the time-of-flight accessory to the new landing position. 10. Repeat the time-of-flight measurements using the low position of the launcher (three measurements) 11. Calculate and record the required averages and percentage error from Task 1, step Did you account for the height of the time-of-flight accessory? What are other possible errors?

13 EF 157 Recitation Instructions Task 3: Horizontal distance same elevation. Equipment: launcher, ball, tape measure, target. Procedure: 1. Using the launch speed calculated in Task 1, step 14, calculate the horizontal distance from the launcher where the ball will hit if the vertical elevation of the target is the same as the exit of the launcher. Do this calculation for the two angles and enter the results on the worksheet. 2. Set the launcher at 30 o and set the target at the theoretical location. 3. Launch the ball and measure the horizontal distance where it hits the target. Record the result on the worksheet. 4. Repeat two more times for the 30 o angle (i.e., there will be a total of 3 data points at this angle). 5. Repeat steps 2-4 for the launcher set at 60 o. 6. Calculate the required statistics and percentage error. Task 4: Horizontal distance different elevation. Equipment: launcher, ball, tape measure. Procedure: 1. Using the y distance measured in Task 1, step 2 and the launch speed calculated in Task 1, step 14, calculate the horizontal distance from the launcher where the ball will hit if the vertical elevation of the target is NOT the same as the exit of the launcher. Do this calculation for both angles and enter the results on the worksheet. 2. Set the launcher at 30 o and remove the target. 3. Launch the ball and measure the horizontal distance where it hits the floor. Record the result on the worksheet. 4. Repeat two more times for the 30 o angle (i.e., there will be a total of 3 data points at this angle). 5. Repeat steps 2-4 for the launcher set 60 o. 6. Calculate the required statistics and percentage error.