Lab background: PurposePreviously, we studied collisions in terms of Newton's 3rd Law. In this lab, we will investigate collisions further and examine the motion of two interacting objects and we will investigate how some of the related quantities change upon collision. We will try to formulate some conclusions about what governs the changes in motion that we observe.SetupYou will use air tracks and gliders to minimize the effects of friction. Two photogates will measure the amount of time it takes the flags to pass and, therefore, allow you to find the glider's speed.The photogates will be used in "gate" mode. Set this up by navigating to Experiment menu ? Set up Sensors submenu ? Show all interfaces ? Click on the picture of the photogate and set it to gate timing and set the length of object to match the length of the object that is passing through the photo gate's infrared detector, situated down at the bottom of the "U."Level the track by observing the motion of a glider - a leveling tool is not sensitive enough. Place a glider between the photogates and adjust the screw feet on the track base such that it does not move. The trials you run will have one glider starting from rest between the photogates, and any motion of the supposedly stationary glider prior to collision contributes to your errors. If the track is bowed or crowned (that is, level on average but not straight) then it may not be possible to get a perfectly motionless glider. If this is true of your track, you may need to gently hold the glider in place with a fingertip at the bottom until the moment before the collision. Be careful to release it with as little motion imparted by the release as possible.Weigh everything you set in motion. This includes gliders and all of their various attachments and weights. (Distinguishing the things you weigh may be a bit tricky; take careful notes.) It may be easiest to weigh things as you go along, recording all the masses at the top of each set of runs.Part I - (Mostly) Elastic CollisionsEquip one glider with a rubber-band bumper on the end facing the other glider and balance the glider with a counterweight on the other side. Make sure the tension in the bumper parts of the rubber band is adequate to "stand off" the other glider.One glider (#1) starts outside the photogates while the other glider (#2) starts between the photogates, motionless. Make sure there is enough space between glider (#2) and the incoming photogate (through which the incoming glider (#1) will come) so that the collision happens after glider (#1) has completely passed through the gate.Make the masses of the gliders unequal by loading all four disk weights onto one of the gliders. Then make one run for each of two cases:? Case 1: Empty glider at rest, loaded glider in motion initially.? Case 2: Loaded glider at rest, empty glider in motion initially.Glider 1 will either "follow" glider 2 through the second gate, come to a complete stop, or "bounce off" glider 2 and return back through the initial gate. If it follows glider 2, then stop glider 2 when it reaches the end of the track to keep it from rebounding and interfering with the motion of glider 1. If glider 1 bounces off glider 2 and goes back through the first gate, then note that its velocity is now negative.After the collision has occurred, the data table will display the gate times and velocities for each event (i.e. each time a glider's flag passed through that photogate and blocked its beam). Select the appropriate glider speeds to use with your calculations.Note that the photogate only records time (and uses this time and the input length to calculate speed), not the direction of motion of the glider. Also note that the software is lying when it displays "velocity" here, since a velocity is a vector and thus should have a magnitude AND direction. Here, the software simply displays "speed," since it provides no information about direction. To keep the directions straight, draw a sketch in your lab notebook to show the situation before and after collision, with the directions of motion indicated. This will help with your analysis.Part II - Totally Inelastic CollisionsA collision in which the two objects stick together and move as a single object with the same velocity is called totally inelastic. Remove the rubber-band bumpers from the gliders. On one glider, mount the attachment with a needle (which may be covered with a small cork in the storage case). Legal note: no matter how unruly your lab partner is, it is generally frowned upon to poke them with the needle, and poking your instructor would certainly not be healthy for your grade. On the other glider, mount the attachment with a hole at the end that is filled with modeling clay. The needle will be "gripped" by the clay in the glider collision, resulting in the two sticking together and "merging" into a single object.Remember to add counterweights to both gliders.Leave one of the gliders empty and load the other with all four of the disk weights. Again, we will begin with one glider at rest. Make sure that glider (#2) is consistently far enough from the first photogate such that the flag on glider (#1) can pass through it entirely before collidingquestions: 1. what assumptions ?can you make in the analysis of this lab? How do they compare to the actual experiment, and what systematic errors may have been introduced by making these assumptions?2. ? Explain what conclusions you can draw from the data by comparing the initial and final relative velocity before, and after each collision, respectively. Describe how your results support these conclusions. (data is in picture)3. ? Explain what conclusions you can draw from your data by comparing the initial and final total momentum before, and after each collision, respectively. Describe how your results support these conclusions. (data in picture)4. Explain what conclusions you can draw from your data by comparing the initial and final total kinetic energy before, and after each collision, respectively. Describe how your results support these conclusions. (data in picture) 5. collisions range anywhere from totally inelastic to totally elastic. Which quantity can be used to determine how elastic a collision is? That is, which quantity is constant across an elastic collision, but completely extinguishable in an inelastic one? 6. How am I a totally elastic collision the design? That is, which quantity is constant across an elastic collision, but changed significantly in an inelastic collision? Elastic collisions are actually defined as collisions in which this quantity is constant.7. ? Conclusion, revisit your scientific question what were your findings? scientific question: how does momentum and kinetic energy of two colliding objects change upon collision?8. Describe how your findings in this lab relate to any every day application of the physics of collisions.

M N O P Q R S Lifilla D. Part I (Mostly) Elastic Collisions Case 1: Initial Conditions: Empty glider at rest, loaded glider in motion Run M, (kg) V1 (m/s) Vit (m/s) M2 (kg) V21 (m/s) Var (m/s) Vapp (m/s) Vsep (m/s) % diff Vrel P1 (kgm/s) Pir (kgm/s) P2 (kgm/s) Pz (kgm/s) |% diff P K 1 ( J ) KIT ( J ) K 21 ( J ) K 2+ ( J ) % DiffK 1 0.411 0.361 0. 133 0.1899 0.000 0.492 0.361 0.359 -0.6% 0.148 0.055 0.000 0.093 -0.2% 0.0268 0.00364 0.000 0.0230 0.6% Case 2: 0.148 0.148 0.0268 0.0266 -0.674 N Initial Conditions: Loaded glider at rest, empty glider in motion 13 14 Run M, (kg) V11 (m/s) Vit (m/s) M2 (kg) V21 (m/s) V21 (m/s) Vapp (m/s) Vsep (m/s) % diff Vrel P1 (kgm/s) Pir (kgm/s) P2 (kgm/s) Py (kgm/s) % diff P K 1 ( J ) Kit ( J ) K21 ( J) K21 ( J) % Diff K 15 2 0.2104 0.641 -0.209 0.3905 0.000 0.406 0.641 0.615 -4.1% 0.135 -0.044 0.000 0.159 -14.8% 0.0432 0.00460 0.000 0.0322 -14.9% 16 17 Part II Totally inelastic Collisions 0.135 0.115 0.043 0.037 18 -0.020 -0.148 19 Case 1: 20 Initial Conditions: Empty glider in motion, loaded glider at rest 21 22 Run M1 (kg) V1 (m/s) M2 (kg) V21 (m/s) V. (m/s) Vapp (m/s) Vsep (m/s) % diff Vrel P1 (kgm/s) P2 (kgm/s) p, (kgm/s) % diff P K 1 ( J ) K21 ( J ) K , ( J ) % Diff K 23 3 0.1995 0.18 0.4004 0.000 0.073 0.180 0.000 100.000 0.036 0.000 0.044 22.0% 0.003 0.000 0.002 -50.5% 24 25 Case 2: 26 Initial Conditions: Loaded glider at motion, empty glider at rest 27 28 Run M1 (kg) V11 (m/s) M2 (kg) V21 (m/s) V. (m/s) Vapp (m/s) Vsep (m/s) % diff Vrel P1I (kgm/s) Pai (kgm/s) p, (kgm/s) % diff P K1 ( J ) K2 ( J ) K, ( J ) % Diff K 29 4 0.4003 0.377 0.1996 0.000 0.262 0.377 0.000 100.000 0.151 0.000 0.157 4.1% 0.028 0.000 0.021 -27.6% 30 31 Case 3: 32 Initial Conditions: Gliders equally weighted, one in motion and one at rest 33 34 Run M1 (kg) V11 (m/s) M2 (kg) V21 (m/s) V. (m/s) Vapp (m/s) Vsep (m/s) % diff Vrel P1 (kgm/s) P2 (kgm/s) p, (kgm/s) % diff P K1I ( J ) K 21 ( J ) K , ( J ) % Diff K 35 5 0.3002 0.378 0.2998 0.000 0.185 0.378 0.000 100.000 0.113 0.000 0.111 -2.2% 0.021 0.000 0.010 -52.1% 36 37 38