Falling Objects P-1
Contents
1. 0 3 0 25 0 2 0 05 2 423 2 625 2 846 3 058 3 269 3 481 3 692 3 904 4 116 4 328 4 529 Sn 2 Time Second s RQ BRIA lo s iiis ia D Be Sh Unzoom Zoom Zoom Select Line ow Grid Graph Table Point Area All Fit Zone Width Functions You can see the position of the ball over time The ball can never bounce back to its original height It loses some of its energy to air resistance internal forces and friction between the ball and the table Click on the Sensor s Module box and then click on the Velocity and Acceleration icon Experiment P 1 Falling Objects Ver 3 6 10 16 NeuLog EF 55 Click on the Graph icon Velocity and acceleration graphs are added E Back Save Open Experiment Experiment IV ee 0 1 Velocity 0 05 2 846 4 116 Q HJA re evs BBM BBL Be Unzoom Zoom Zoom Select Line Show Grid Graph Table Point Area All Fit Zone Width Functions 2 058 3 269 3 481 2 69 Time Second 56 We can see in the graphs that when the ball falls down it gains velocity in a constant rate then it bounces back up and loses its velocity in the same rate but in the opposite direction therefore the acceleration is still positive The acceleration at the moment the ball changes its direction is negative when the positive direction is downwards When the ball hits the groynd its velocity quickly turns from positive to negative this transition happens in an instant thus the acceleration graph has2. and then click on the Velocity and Acceleration icon Click on the Graph icon H Velocity and acceleration graphs are added Open Experiment Experiment NeuLog Al Velo 0 5 0 0 2 0 3692 0 2241 0 07912 0 06589 0 2109 2 Time Second R RIA lo a3 Unzoom Zoom Zoom Select Line Show Grid Graph Table Point Area All Fit Zone Width Functions Save your graph We can see that the velocity increases in relatively constant rate thus the cup s acceleration is constant Experiment P 1 Falling Objects Ver 3 6 10 14 NeuLog EF 43 Move the utility stand to the center of the table 44 Put the utility stand on a basket or a box Set up the motion sensor as high as you can 45 Change the experiment duration to 5 seconds and close the Trigger function Experiment P 1 Falling Objects Ver 3 6 10 47 48 49 50 Sl 52 53 54 15 NeuLog EF Let us repeat the experiment with the ball Hold the ball around 25 cm below the motion sensor Click on the Run experiment icon C Release the ball after one or two seconds and let it bounce Click on the Zoom fit icon a or alternatively in order to focus on the desired range click on the Zoom icon Q locate the mouse cursor at a point above the graph and press its left button keep it pressed and create a rectangle that includes the whole range Your graph should be similar to the following 0 6 0 55 0 5 0 45 0 4 0 35
3. 1 NeuLog EZ Experiment P 1 Falling Objects amp Objectives To study the motion of falling objects To learn about the effect of air resistance force To study motion parameters of a bouncing ball Modules and Sensors PC NeuLog application USB 200 module NUL 213 Motion logger sensor Equipment and Accessories Utility stand Right angle clamp Extension clamp Paper baking cup Paper cup Ball Ball pump Basket or box The items above except for the basket are included in the NeuLog Mechanics kit MEC KIT Experiment P 1 Falling Objects Ver 3 6 10 2 NeuLog EJ Introduction The position or displacement of a moving object is marked by the letter x The object s velocity is marked by the letter v The velocity is determined by the ratio between the change in position and the time it took for the object to move The formula is v average x final x initial t final t initial When the velocity is constant it can be described as in the formula above When the velocity changes with time dividing the change in position by the time will give us the object s average velocity In order to calculate the object s momentary velocity v t we divide a very small section of the position change by the time difference Acceleration is the rate at which an object changes its velocity and it is marked by the letter a The acceleration is determined by the ratio between the change in velocity
4. The shape of the paper baking cup Is as follows This shape balances it while falling Hold the paper baking cup around 25 cm 0 25 m below the motion sensor and check that this distance appears in the sensor s module box on the screen Click on the Run Experiment icon LJ to start the measurement The message Waiting for Trigger should appear on the screen We use the trigger function because the experiment duration is very short Release the paper baking cup and observe its fall to the floor Experiment P 1 Falling Objects Ver 3 6 10 19 20 21 22 23 24 20 9 NeuLog EJ Click on the Zoom fit icon be Your graph should be similar to the following NeuLog Al EA To E D Back Experiment Erase Single Setup Experiment Step 0 2 0 5 0 0 1 0 2 0 3 0 4 0 6 0 7 0 8 0 9 1 Time Second Py RFA ks ES BBL Be Unzoom Show All ion Zoom Zoom Select Line Grid Graph Table Point Area Fit If your graph is not similar to the example graph check that the paper baking cup moves against the motion sensor all the time and check that there are not any objects that are sending an echo to the sensor save your graph Analyze the graph and identify what happens to the paper baking cup velocity and _ acceleration during the measurement To calculate the average velocity click on click on the Select Zone icon ke and select the part of the graph that represents the paper baking cup v
5. and the time it took The formula is a average v final V initial t final t initial The formula above describes average acceleration or constant acceleration In order to calculate the object s momentary acceleration a t we divide a very small section of the velocity change by the time difference These concepts will help you understand the principles of falling objects One of the classic questions in physics is If we throw two objects one with a mass of 100 g and one with a mass of 1000 g from a tall building which one will hit the ground first The intuitive answer is that the heavier object will hit the ground first 300 years ago Galileo proved that the two objects will hit the ground together When an object falls it always increases its velocity towards the ground In other words the object accelerates The acceleration of all free falling objects is the same Experiment P 1 Falling Objects Ver 3 6 10 3 NeuLog EF This law is correct as long as there is no factor that influences the falling object such as air The air applies force on the body thus decreases its velocity towards the ground according to the ratio between the surface area and its weight The force applied by the air is called air resistance When the object s surface area is large and its weight is small the air resistance force will decrease its falling speed This is why we use a parachute to lower the falling speed of p
6. aratroopers In this experiment we will examine falling objects We will measure the position of a paper cup and a paper baking cup over time and also velocity changes during the fall When some objects fall they bounce right up but do not reach the same height in which they were dropped In the second part of the experiment we will measure the position velocity and acceleration of a bouncing ball over time Experiment P 1 Falling Objects Ver 3 6 10 4 NeuLog EJ Procedure Experiment setup 1 Set up the experiment as shown in the picture below 2 Use the pump to inflate the ball 3 Attach the motion sensor to the utility stand using the right angle clamp and the extension clamp The motion sensor should be aimed at the floor Experiment P 1 Falling Objects Ver 3 6 10 5 NeuLog EJ Sensor setup 4 Connect the USB 200 module A to the PC 5 Check that the motion sensor is connected to the USB 200 module Note The following application functions are explained in short It is recommended to practice the NeuLog application functions as described in the user manual beforehand 6 Run the NeuLog application and check that the motion sensor is identified Experiment P 1 Falling Objects Ver 3 6 10 6 NeuLog EF settings 7 Click on the On line Experiment icon Ga in the NeuLog main icon bar 8 Click on the Sensor s Module box 9 Click on the Range button 10 Select the m meter radio butto
7. elocity Click on the Show functions icon s and then click on the Motion sensor button on the left of the screen Experiment P 1 Falling Objects Ver 3 6 10 10 NeuLog EJ 26 Click on the Linear fit button to get the equation gi s A B Back Experiment Erase Setup Experiment Undo all functions 0 2 R Ita IQ le a Time Second HE M See AS Unzoom Zoom Zoom Select Li Grid Graph Table Point Area All Fit Zone Width Functions Linear Motion 1 018x 0 3355 We can see that in this range the position versus time is a linear graph and it means that the velocity is constant In our example above the value of the velocity is V 1 018 m s 27 Click on the Back button on the left of the screen 28 Click on the Sensor s Module box and then click on the Velocity and Acceleration icon Experiment P 1 Falling Objects Ver 3 6 10 29 30 11 NeuLog EZ Click on the Graph icon Velocity and acceleration graphs are added a pE G D CSES a 2 B S t Experiment Erase Single Run Save Open Setup Experiment Step Experiment Experiment Experiment lt lt Pre Trigger 0 Velocity Qima k BB BS Unzoom Zoom Zoom Select Line Show Grid Graph Table Point Are i Zone Width Functions The velocity of the paper baking cup starts from zero increases and then becomes constant The graph is not ideal because any small movement of the paper baking cup affects the measured veloci
8. n to change the sensor s mode to position NeuLog 0 a p E D Commas Back Experiment Erase Single Run Save Open Experiment Step Experiment Experiment Experiment 0 160 Motion id 1 m Range Distance Distance Velocity amp Acceleration Velocity Acceleration EE BBL Be Grid Graph Table Point Area 11 Click on the Experiment Setup Gees icon Experiment duration to 1 second sampling rate to 20 per second Trigger level 0 3 m rise Experiment P 1 Falling Objects Ver 3 6 10 7 NeuLog EF Testing and measurements Note The sensor measures the distance from an object by sending a short pulse of sound that we cannot hear ultrasonic and measures the time it takes the echo to return The sound beam angle is approximately 45 The sensor measures the time of the first received echo Make sure to remove any items located In the beam range between the motion sensor and the floor 12 Make sure that the motion sensor is well directed to the floor Observe that the position distance from the sensor values already appear in the sensor s module box 13 Check that the measured distance is the height of the sensor from the floor Set the motion sensor to be around 1 m from the floor Experiment P 1 Falling Objects Ver 3 6 10 14 15 16 17 18 8 NeuLog EF Take a paper baking cup and let it fall to the floor Check that it falls in a straight line observe its fall from above Note
9. peaks of negative acceleration every time the ball hits the ground Experiment P 1 Falling Objects Ver 3 6 10 17 NeuLog EJ Summary questions Lis Explain why the velocity of the paper baking cup becomes constant and does not increase as the velocity of the paper cup Air resistance force also acts in nature Explain how plants use air resistance for seed dispersal Why can some balls bounce like the one you used and others cannot Experiment P 1 Falling Objects Ver 3 6 10
10. ty Click on the Table icon EE and look for the part which includes the values from the linear part of the graph Linear Motion ID 1 m 1 velocity Motion D 1 1 0 44 0 73 0 69 0 75 0 4402 122 0 4402 0 9 0 4402 1 17 0 54 0 9 0 5899 0 97 0 5899 1 11 0 5899 0 89 0 7397 1 1 0 7896 1 01 0 7896 1 07 Experiment P 1 Falling Objects Ver 3 6 10 31 32 33 34 35 36 37 12 NeuLog EJ The velocity values are similar to V 1 018 m s the calculated value What is the acceleration of the paper baking cup when its velocity is constant Let us repeat the experiment with the paper cup The cup has about the same shape as the paper baking cup but it is much heavier Click on the Erase experiment icon in order to erase the graph Place the paper cup on the starting position and click on the Run Experiment icon to start the measurement Release the paper cup and observe its fall Click on the Zoom fit icon a Your graph should be similar to the following NeuLog a Unzoom Zoom Zoom Select Line Grid Graph Table Point Area Zone Width Functions 0 2 o 0 1 0 2 0 3 0 4 0 5 0 6 0 7 0 8 0 9 O R Time Second eY Q EALE k Erme Save your graph Experiment P 1 Falling Objects Ver 3 6 10 38 39 40 41 42 13 NeuLog EF Observe the graph and see that it is not linear The cup accelerates all the way to the floor Click on the Sensor s Module box
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