Phy201 General Physics I Laboratory Instructor Tony Zable 1 1 14 2019 Experiment Momentum Impulse in Collisions Video Objectives To utilize momentum carts to investigate the nature of different types of collisions To perform video motion analysis on elastic and inelastic collisions to explore the principle of momentum conservation graphically and numerically To observe how momentum impulse and kinetic energy are transferred during elastic and inelastic collisions Materials a digital USB webcam camera LoggerPro Software 2 motion carts Pasco collision track a meter stick Introduction The impulse momentum theorem relates impulse the average force applied to an object times the length of time the force is applied and the change in momentum of the object F t mvv mvi Here we will only consider motion and forces along a single line The average force F is the net force on the object but in the case where one force dominates all others it is sufficient to use only the large force in calculations and analysis For this experiment a dynamics cart will roll along a level track and collide with a second cart Using video technology you will analyze the collision before during and after Using Logger Pro to develop velocity time graphs you will test the Law of Conservation of Linear Momentum Part A Initial Measurements Camera Set up 1 Obtain 2 matched collision carts A matched cart pair will allow you to perform both elastic and inelastic collision experiments 2 Measure the mass of both carts using a digital scale 3 Record the mass of each cart in the table below 4 Plug webcam into the USB slot on the computer 5 Open LoggerPro 6 Using the mouse select Insert Video Capture Camera Settings 7 Use the Exposure controls to i decrease the shutter speed to 1 300 sec ii increase the gain to roughly 60 to 80 i e adjust the slide control to the right to improve contract iii set the White Balance to Fluorescent 9 Close the Camera Settings window Part B An Inelastic Collision Visualized File Name Phy201 General Physics I Laboratory Instructor Tony Zable 2 1 14 2019 Introduction In this section you will set up and perform video motion analysis on an inelastic collision to analyze the momentum and energy transfer that occurs between the two collision carts Procedure Inelastic Collision 1 Initial Set Up and Video Capture a Level the collision track b Orient two collision carts so that when they will stick together during impact c Set Cart 1 at one end of the track and Cart 2 near the center d In LoggerPro select Insert Video Capture Before recording video go over the following Hints for cameraman section e Hints for cameraman 1 The camera must remain completely still during the digital recording process 2 Be sure the track and both carts are clearly in the camera field of view 3 Place a meter stick in the field of view to be used as a reference length in LoggerPro later on 4 Keep the track parallel to the horizontal direction in the field of view and focus the camera straight on to minimize parallax or visual artifacts 5 The video file should capture the entire experiment from just before the initial push through the post collision motion Note the movie will be saved as an AVI format movie avi f To record video click on Start Capture g When the cameraman and the experimenter s are ready start filming the movie then give Cart 1 a good push toward Cart 2 h To end recording click on Stop Capture A Video window will open up in LoggerPro View your movie in the camera to verify that it captured what you want 2 Video Motion Analysis a Resize and move the movie field if necessary for viewability and convenience b Use the QuickTime buttons to review the movie c Click on the movie window and select the Video Analysis button right hand corner d Scale the movie using a meter stick as your reference e Select the positions for cart 1 in each frame If possible to try and get 10 20 points before and 10 20 points after the collision File Name Phy201 General Physics I Laboratory Instructor Tony Zable f 3 1 14 2019 Using the QuickTime buttons go back to the first frame where you started selecting points for cart 1 Click on the Set Active Point button then select the positions for cart 2 for the same frames as cart 1 h Right mouse click on movie frame and select sent to back to better view graphs i Object Observe the graph window on the right side of the display Select XVelocity and X Velocity 2 for the y axis Mass kg vaverage m s Before Collision paverage KEaverage vaverage m s After Collision paverage KEaverage Cart 1 Cart 2 Summary of Momentum and Energy Change Object Mass p KE kg Cart 1 Cart 2 Analysis 1 Observe the velocity graphs for each cart Describe them 2 What was the average velocity of Cart 1 and Cart 2 before the collision Use the statistics feature of Graphical Analysis to determine this value from the graph 3 Calculate the average momentum of Cart 1 and Cart 2 before the collision Record in the above table 4 Repeat steps 2 and 3 for carts 1 and 2 after the collision 5 Calculate the change in momentum p for both cart 1 and cart 2 Record values in the table 6 How does pcart 1 compare with pcart 2 7 What does your answer to the previous question imply about the total system momentum before during and after this particular collision File Name Phy201 General Physics I Laboratory Instructor Tony Zable 4 1 14 2019 8 Create a new calculated column in LoggerPro called Total Momentum Define its formula as the total momentum of Cart 1 and Cart 2 9 Insert New Graph Select Total Momentum for the y axis Observe the Total Momentum vs time graph 10 Does the total momentum graph have a discernible slope Select the points in the graph using your mouse the click on the Linear Fit button to determine this slope Slope of Total Momentum vs time Slope Units 11 What do you think the significance of this slope might be 12 Calculate the KE and KE for each cart Record in the above table 13 How does KEcart 1 compare with KEcart 2 14 Create a new calculated column in LoggerPro called Total Energy Define its formula as the total KE of Cart 1 and Cart 2 15 Click on the graph window and select Total Energy for the y axis Observe the Total Energy vs time graph 16 Describe the TE vs time graph Does its appearance surprise you File Name Phy201 General Physics I Laboratory Instructor Tony Zable 5 1 14 2019 Part C An Elastic Collision Visualized Introduction In this section you will set up and perform video motion analysis on an elastic collision to