tangible_1D_Collisions_S23

pdf

School

University of South Carolina *

*We aren’t endorsed by this school

Course

211

Subject

Mechanical Engineering

Date

Oct 30, 2023

Type

pdf

Pages

Uploaded by CorporalMaskKomodoDragon8

1-D Collisions Equipment (cabling not shown): • per group: dynamics track, 2 magnetic/velcro carts, 2 photogates, photogate mounting posts, LabQuest , END STOPS FOR TRACKS • per table: digital mass balance, extra weight bars to trim mass (not shown in setup pictures) • do not include the wide metal flags in the pictures – use small ones instead

Introduction Key question : What quantity is always conserved in a collision between objects? The answer we’re looking for in this activity is “linear momentum,” but conservation is linked to the definition of the system of objects as well. Keep in mind that a “collision” is about the moment of impact, and not before or after that moment. The larger topic of momentum conservation concerns the times before, at, and after the impact, and can be complicated by the presence of external forces. In this activity, it is important to remove the external force of gravity by leveling the dynamics tracks. The external force of friction is minimized but not eliminated by using rolling carts. Using the dynamics track and carts, you will perform “elastic” and “inelastic” collisions to mimic the scenarios described in the warm-up. The terms “elastic” and “inelastic” refer to the kinetic energy in the system: • “Elastic” or “perfectly elastic” collisions are ones in which the carts bounce off each other. The carts may continue in the same direction, or they may change direction because of the collision. • “Perfectly inelastic” collisions are ones in which the carts stick together after colliding. General Procedure: • Measure the masses of the carts with the digital mass scale (the conservation of momentum does not require that the mass of each cart be the same). You may trim the mass of each cart to make it heavier as needed or desired (use bars or small shim masses). • Measure the speeds before and after the collisions with the photogates. o Begin by attaching a narrow flag to each cart. o If not already done, using mounting posts, attach the photogates on the track so that the cart can pass under them as the cart flag breaks the sensor path (see diagrams). o Using the measured time that the flag breaks the sensor path (via the LabQuest) and the flag length, calculate the speed of the carts as they move past the photogates. If you set the software up correctly, it will automatically calculate the speeds for you! • Compute the total momentum of the system before and after the collisions, paying close attention to signs . • Enter your data into the shared Google Spreadsheet for comparison Predictions are made based on the principle of conservation of momentum alone. Your task is to determine how well the experimental results match the predictions, to within an experimental uncertainty. This activity is about quality and not quantity . Due to limitations of time, each group will collect and evaluate data for only one option for each exploration. All data will be recorded in a shared Google Spreadsheet.

With care, you should be able to get results that agree to within about 1%. Play with the setup for a while so that you are confident that you can do a really good experiment. Then, take relatively little time to perform the experiment itself. Different groups can compare results. Refer to the accompanying document “ Logger Pro Operation ” for details in how to set up the instrumentation for this activity. Exploration 1 – Elastic collisions: You will be assigned to investigate one of the options below: o Option 1: M 1 ≈ M 2 o Option 2: M 1 > M 2 o Option 3: M 1 < M 2 The figure below shows the initial conditions of the collision, the before collision situation and a potential after collision situation. The flag length is exaggerated for illustration. Assume cart 1 is the incoming cart; cart 2 is at rest. The carts will be “collided;” arrange the carts so their magnets are facing each other so they can provide a force by which momentum is exchanged or transferred (without damaging the carts!). Using the photogates and the LabQuest, set up to measure 3 speeds: flag flag INITIAL flag flag BEFORE COLLISION flag flag AFTER COLLISION photogate photogate

Your preview ends here

Eager to read complete document? Join bartleby learn and gain access to the full version

Access to all documents
Unlimited textbook solutions
24/7 expert homework help

1. The incoming speed of cart 1. 2. The rebound speed of cart 1 (if any). 3. The recoil speed of cart 2. Before you begin, predict the behavior of the carts after the collision for your assigned investigation. Enter this prediction on the worksheet. Measure the mass of two magnetic carts (cart 1 and cart 2). Launch cart 1 so that it has a constant speed going through the first photogate. On the worksheet, record the “blockage time” of the cart 1 flag when incoming, the cart 1 flag when rebounding. and the cart 2 flag as it recoils. Use the blockage times and the flag lengths to calculate the three speeds. Some experimental suggestions: • A larger incoming speed may minimize the effect of friction, but excessive speed may create other issues. Search for a sweet spot. • Trim the masses up or down to help find a sweet spot. If you trim the mass, do not forget to reweigh . • Don’t spend too much time trying to make measurements that are too precise . Focus more on getting reasonably accurate velocity values rather than precisely wrong ones! For your assigned investigation, determine whether momentum is conserved (that is, that the momentum before and after the collision is the same in both magnitude and direction). How well do the experimental results match the predictions? If you think momentum is not conserved in the experiment, list reasons why this might be the case. Record all measurements and analysis on the worksheet and the provided Google Spreadsheet. Exploration 2 – Inelastic collisions: You will be assigned to investigate one of the options below (same option as Exploration 1): o Option 1: M 1 ≈ M 2 o Option 2: M 1 > M 2 o Option 3: M 1 < M 2 The figure below shows the initial conditions of the collision, the before collision situation and a potential after collision situation. The flag length is exaggerated for illustration.

Assume cart 1 is the incoming cart; cart 2 is at rest. The carts will again be “collided;” however, for this exploration, arrange the carts so their Velcro patches are facing each other so they can catch and hold while colliding. Using the photogates and the LabQuest, set up to measure 2 speeds: 1. The incoming speed of cart 1. 2. The final speed of cart 1 and cart 2 stuck together. Before you begin, predict the behavior of the carts after the collision for your assigned investigation. Enter this prediction on the worksheet. Measure the mass of two “Velcro” carts (cart 1 and cart 2). Launch cart 1 so that it has a constant speed going through the first photogate. Record the “blockage time” of its flag when incoming. As a result of the collision, the carts stick together and continue moving. Record the blockage time of the combined carts as they continue moving. Use the flag lengths to calculate the two speeds. Some experimental suggestions: • A larger incoming speed may minimize the effect of friction, but excessive speed may create other issues. Search for a sweet spot. • Trim the masses up or down to help find a sweet spot. If you trim the mass, do not forget to reweigh . flag flag INITIAL flag flag BEFORE COLLISION flag flag AFTER COLLISION photogate photogate

• The flags of the combined cart after collision will break the photogate twice. Discuss this issue and implement a method to measure this speed correctly with your group members. • Don’t spend too much time trying to make measurements that are too precise . Focus more on getting reasonably accurate velocity values rather than precisely wrong ones! For your assigned investigation, determine whether momentum is conserved (that is, that the momentum before and after the collision is the same in both magnitude and direction). How well do the experimental results match the predictions? If you think momentum is not conserved in the experiment, list reasons why this might be the case. Record all measurements and analysis on the worksheet and the provided Google Spreadsheet. Exploration 3 – Head on Collisions (if there is time) Explore what will happen if the two carts in your assigned option are moving toward each other at the same speed. Deliverable : There are two deliverables for this activity: the group worksheet is to be turned in by the end of studio and the responses to the follow-up INDIVIDUAL questions are to be turned in at the beginning of Studio 13.

Your preview ends here

Eager to read complete document? Join bartleby learn and gain access to the full version