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Homework Help: How the angle of launch affect the range?

  1. Apr 6, 2017 #1
    1. The problem statement, all variables and given/known data
    I'm about to conduct an experiment about factors that affect the flight of an elastic band.
    The aim of this experiment is to find how the angle of launch, when shooting a rubber band, affects the range or distance of the shot.
    Do you suggest to consider the drag force? like, for example, show the differences on how with and without air resistance the range is affected?

    Variable list:
    • Independent Variable
      • Angle of launch
    • Dependent Variable
      • Range or distance
    2. Relevant equations
    Without air resistance these formulas are applicable:
    range_equation_initial_velocity.png range_equation_gravity.png vertical_velocity_equation_time.png
    More examples of equations

    With air resistance:

    3. The attempt at a solution
    Like I said I will be doing a lab report, so I thought of considering the drag force but I don't know much about it, however, do you think its a good idea to show the difference? or should I show the difference in vertical height?
  2. jcsd
  3. Apr 6, 2017 #2


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    Gold Member

    Does it have to be an elastic band that you launch? If not, consider using an elastic band to launch something else, like a marble or ball bearing. I suggest that would give you much more analyzable and repeatable results. Launching an elastic band repeatably might be a challenge, and modelling it would certainly be. Setting up a slingshot sort of launch mechanism seems more straightforward and amenable to modelling with basic equations you can learn to apply without yet knowing calculus. You can ignore the effects of drag on a small spherical object and clearly see that the range you predict for different launch angles matches pretty well with your equations, if you have properly calibrated the energy in the stretched elastic launcher.

    To model drag on an elastic band would require pretty advanced techniques, imo so elaborate that most would consider it a measurement problem, not an analysis problem (meaning its too much trouble to calculate it, just measure it).
  4. Apr 6, 2017 #3
    Alright then i will be measuring the highest peak, max height, time taken, velocities and graph the results. Do you think this will be enough?
  5. Apr 6, 2017 #4


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    What is the difference between those two?

    Out of curiosity, how will you measure this?

    If your goal is to test specific calculations you make that predict things like max height and compare them to experimental results, then you should look at the equations you plan to use and decide which of the results of your equations you are able to measure to assess if its enough to make a good experiment. One comment I have is that you started out stating you want to measure range vs launch angle, so I would expect to see both of those things in your list.
  6. Apr 6, 2017 #5


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    I am not sure what level of education you are at or how much effort is expected from you in this exercise. It may be that I am putting you in over your head with some of my suggestions - if it feels that way, below is a link to a very simple experiment using only rubber bands that will let you explore most of the concepts you are talking about.


    edit: I just saw your other thread on the same topic. Probably best to keep all the discussion in one thread.
    Last edited: Apr 6, 2017
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