- Lab 10a Freefall Picket Fence Introduction A Picket Fence Is A Clear Plastic Strip With Uniformly Spaced Opaque Bands E 1 (42.64 KiB) Viewed 36 times
- Lab 10a Freefall Picket Fence Introduction A Picket Fence Is A Clear Plastic Strip With Uniformly Spaced Opaque Bands E 2 (50.17 KiB) Viewed 36 times
- Lab 10a Freefall Picket Fence Introduction A Picket Fence Is A Clear Plastic Strip With Uniformly Spaced Opaque Bands E 3 (37.68 KiB) Viewed 36 times
- Lab 10a Freefall Picket Fence Introduction A Picket Fence Is A Clear Plastic Strip With Uniformly Spaced Opaque Bands E 4 (35.24 KiB) Viewed 36 times
- Lab 10a Freefall Picket Fence Introduction A Picket Fence Is A Clear Plastic Strip With Uniformly Spaced Opaque Bands E 5 (46.11 KiB) Viewed 36 times
- Lab 10a Freefall Picket Fence Introduction A Picket Fence Is A Clear Plastic Strip With Uniformly Spaced Opaque Bands E 6 (46.11 KiB) Viewed 36 times
- Lab 10a Freefall Picket Fence Introduction A Picket Fence Is A Clear Plastic Strip With Uniformly Spaced Opaque Bands E 7 (51.72 KiB) Viewed 36 times
- Lab 10a Freefall Picket Fence Introduction A Picket Fence Is A Clear Plastic Strip With Uniformly Spaced Opaque Bands E 8 (31.37 KiB) Viewed 36 times
- Lab 10a Freefall Picket Fence Introduction A Picket Fence Is A Clear Plastic Strip With Uniformly Spaced Opaque Bands E 9 (36.85 KiB) Viewed 36 times
- Lab 10a Freefall Picket Fence Introduction A Picket Fence Is A Clear Plastic Strip With Uniformly Spaced Opaque Bands E 10 (56.28 KiB) Viewed 36 times
- Lab 10a Freefall Picket Fence Introduction A Picket Fence Is A Clear Plastic Strip With Uniformly Spaced Opaque Bands E 11 (40.3 KiB) Viewed 36 times
- Lab 10a Freefall Picket Fence Introduction A Picket Fence Is A Clear Plastic Strip With Uniformly Spaced Opaque Bands E 12 (54.91 KiB) Viewed 36 times
- Lab 10a Freefall Picket Fence Introduction A Picket Fence Is A Clear Plastic Strip With Uniformly Spaced Opaque Bands E 13 (52.71 KiB) Viewed 36 times
Taking Data Average Time v. im) 1. Start recording data, then drop the Mcket Fence through the Photogate. Stop recording data. 2. the Picket Fence hits the Photogate, or if it rotates too much. should take another run. You should have seven entries in the data table. These are the times that each of the seven bands on the Picket Fence broke the Photogate beam Table 1. Calculating Average Velocities Block Times M (5) 1 0.07927 2 0.13980 0.06053 3 0.17803 0.03823 4 0.20058 0.03055 5 0.23484 0.02626 5 0.25034 0.02350 7 0.27954 0.02120 0.10954 15892 0.19330 0.22171 0.24659 0.26894 0.82604 1.10707 1.63600 1.90404 2.12766 2.35849 Calculations 9 3. Calculate the difference between block times and enter them into the column in the table. Note that you may have to increase the number of decimal places in each column to see the difference between the numbers. You can do this using the tool at the top of the graph. 4.Calculate the average speed of the Micket Fence during the time between the first and second block AX V Ax ΔΕ t- where is the time each block occured is the spacing between the bands on the Picket Fence, and is measured from the beginning of one band to the beginning of the next you can measure over several bands to get a more accurate value x Enter your calculated average speeds into the table. You will end up with only velocities in your table 6. To calculate the time that the average velocity actually occurred calculate the average time between the lock Times. Add adjacent Black Times and divide by 2. Enter these times into the table under Average Time 2.6 2.4 2.2 2.0 18 16 & 14 $12 10 08 0.6 0.14 0.16 0.22 0.10012 0.26 0.20 Average Time Avg Velocity vs. Time
2.4 6. Select a Linear Curve Fit from the graph toolbar, 7. What is the physical meaning of the slope? Does have units? What is the uncertainty in your value? 8. Compare to the accepted value using the error calculation www 22 Set 2.0 Line ME+D m-9.55 0.052 b=-0.215 001) T-1000 18 9% error Measured Accepted Accepted 2100 VA 16 9. Was your value too high or too low? What might account for that? 1.4 1.2 10 03 7. Acceleration, the units is mus 2. The uncertainty is 0.062 6. Accepted value is 95 m2, acceleration due to gravity measured values -9.55 ms - 2. %erroris equal to -255% 9. The value was too low. Friction between the fingers releasing the bar, air resistance, and being at a higher elevation can all acount for a lower measured value. 0.10 0.12 0.14 0.16 0.22 0.24 0.26 18 0.20 Average Times Average Vincity vs time
Analysis 30 Une M 20 9624 061 000 27 26 in the previous sections, you used the photogate only to measure the time of black and then calculated the speeds by hand. The computer can also be configured to calculate these speeds automatically, allowing you to take multiple runs in a short period of time. This is in the Timer Setup which you can open at le 1. Start recording data, then drop the Picket Fence through the Photogate as before. Stop recording data 2. The speed s time data for this run will be graphed right. Select a Unear Curve it to find the acceleration as before 3. Repeat several times to get an average value. Also record your highest value 4. In the set up procedure, you were instructed to start the Picket Fence as low as possible. This decreases the speed and lowers the amount of a drag Ty letting go of the Picket Fence higher up to see if you can affect the measured cceleration. Do you get a lower value Speedome 24 22 2.1 2.0 The average of all these 38m2. The 62 certo happen because arrance ws the accelerate of the face it to reach terminal velocity while it is a through these The 102 m2 acceleration could have happened because the tentas at an angles the measurements could be 150 256 1.60 The Speed
Lab 10A: Freefall Picket Fence Introduction A Picket Fence is a clear plastic strip with uniformly spaced opaque bands Each opaque band blocks the photogate beam, and the time from one blockage to the next becomes shorter as the velocity of the falling Picket Fence increases. Using the known distance between the leading edge of each band, and the time interval between photogate blocks, the student calculates the average velocity of the Picket Fence for each interval. The slope of the graph of average velocity versus time gives the acceleration of the falling object Equipment 02 items 1 Photogate 1 Picket Fence 1 Mounting Rod 1 Table Clamp 1 Mult-Clamp 1 90-cm Rod 1 No Bounce Pad Part Number ME 9498A ME-9377A SA-9242 ME-9472 ME-9507 ME-8783 SE 7347 The Table Clamp is used to support the 90 cm Rod. The yellow No-Bounce Pad is used to protect the falling Picket Fence when it reaches the table The Photogate must be plugged into Digital Input 1 V Leguts 1 Dropping arence
Taking Data 1. Start recording data, then drop the Mcket Fence through the Photogate. Stop recording data 2. W the Picket Fence hits the Photogate, or if it rotates too much, y should take another run. You should have seven entries in the data table. These are the times that each of the seven bands on the Picket Fence broke the Photogate beam. Average Time (8) VIE Im Table 1. Calculating Average Velocities Block Times At (s) (s) 1 0.07927 2 0.13980 0.06053 0.1780) 003823 4 0.20858 0.03055 5 0.23484 0.02626 6 0.25834 0.02350 7 0.27954 0.02120 8 Calculations DUA 0.10954 0.15892 0.19330 0.22171 0.24659 0.26894 0.62604 130787 1.63666 1.90404 2.12766 235649 9 2.0 2.4 NNNN 2.2 VA 3. Calculate the difference &t) between block times and enter them into the column in the table. Note that you may have to increase the number of decimal places in each column to see the difference between the numbers. You can do this using the tool at the top of the graph 4.Calculate the average speed of the Acket Fence during the time between the first and second block Ax V= Attt where t is the time each block occured. Ax is the spacing between the bands on the Picket Fence, and is measured from the beginning of one band to the beginning of the next. You can measure over several bands to get a more accurate value of Enter your calculated average speeds into the table. You will end up with only velocities in your table 6. To calculate the time that the average velocity actually occurred calculate the average time between the Block Times. Ade adjacent Block Times and divide by 2. Enter these times into the table under Average Time Set 2.0 1 16 a 1.4 $ 12 1.0 08 06 NOSSOS 0.10 0.12 0.14 0.16 0.22 0.24 0.26 0.18 0.20 Average Times Avg Velocity vs. Time
Average Time (s) V-Ax/AT (m/s) y ca Table 1. Calculating Average Velocities Block Times At (s) (s) 1 0.07927 2 0.13980 0.06053 3 0.17803 0.03823 4 0.20858 0.03055 5 0.23484 0.02626 6 0.25834 0.02350 0.10954 0.82604 0.15892 1.30787 4 0.19330 1.63666 0.22171 1.90404 0.24659 2.12766 m the 7 0.27954 0.02120 0.26894 2.35849 8 8 9
V=Axat Set x v=Ax/At (m/s) 2.6 2.4 2.2 2.0 1.8 1.6 1.4 1.2 1.0 0.8 0.6 0.22 0.26 0.24 0.16 0.10 0.12 0.14 0.18 0.20 Average Time (s) Avg Velocity vs. Time
2.4 VAXA 2.2 Set x 2.0 Unear mx + b m = 9.55 +0.062 b = -0.215 + 0.013 - 1.000 1.8 V=Ax/At (m/s) 1.6 1.4 1.2 1.0 0.8 0.26 0.24 0.22 0.16 0.14 0.12 0.10 0.18 0.20 Average Time (s)
24 6. Select a Unear Curve Fit from the graph toolbar. 7. What is the physical meaning of the slope? Does it have units? What is the uncertainty in your value? 8. Compare to the accepted value using the % error calculation VAN 1 2.2 Set 2.0 Linear mx + b m-9.55 0.062 b=0.215 + 0.013 1.000 18 % error = Measured-Accepted Accepted x 100 tims 1.6 9. Was your value too high or too low? What might account for that? 14 10 OB 7. Acceleration, the units is m/s2. The uncertainty is 0.062 8. Accepted value is .9.8 m/ s2, acceleration due to gravity, measured value is -9.55 m/s2. % error is equal to 2.55% 9. The value was too low, Friction between the fingers releasing the bar, air resistance, and being at a higher elevation can all acount for a lower measured value 0.14 0.26 0.22 0.16 0.100.12 0.24 0.18 0.20 Average Times Average Velocity vs. Time
3.0 2.9 Linear mt + b m-9.62 +0.42 b = -12.8 +0.67 r=0.996 2.8 2.7 2.6 2.5 Speed (m/s) 2.4 2.3 Run #4 2.2 2.1 2.0 1.54 1.56 1.60 1.62 1.64 1.58 Time (s)
3.0 UN 29 9.62 042 D-123 +0.67 0996 2.8 Analysis In the previous sections, you used the Photogate only to measure the time of block, and then calculated the speeds by hand. The computer can also be configured to calculate these speeds automatically, allowing you to take multiple runs in a short period of time. This is in the Timer Setup which you can open at left. 1. Start recording data, then drop the Picket Fence through the Photogate as before. Stop recording data. 2. The speed vs. time data for this run will be graphed at right. Select a Linear Curve Fit to find the acceleration as before 2.7 2.0 25 Speed (m/ 24 Run 4 23 3. Repeat several times to get an average value. Also record your highest value. 4. In the set-up procedure, you were instructed to start the Picket Fence as low as possible. This decreases the speed and lowers the amount of air drag. Try letting go of the Picket Fence higher up to see if you can affect the measured acceleration. Do you get a lower value? 22 21 20 162 The average of all the slopes is 9838 m/s2. The 9.62 m/s2 acceleration happens because air resisance slows the acceleratio of the fence, causing it to reach terminal velocity while it is passi through the sensor The 102 m2 acceleration could have happened because the foncwas at an angle so the measurements could be of 1.64 160 1.54 150 1.58 Tue Speed me