Angle, range and extension in projectile motion?

  • #1
We have a trebuchet which we can adjust the launch angle, and how far the rubber band is pulled back (extension). The rubber band spring constant is constant throughout. I need to find the relationship between the angle of launch and range, and the relationship between the extension and range. This should allow me to finally be given a range, and adjust the angle and extension so as to make the mass land at that spot.



We are given no equations, but I have been using the kinetic and gravitational potential energy equations.


I have trial data in which I have calculated the spring constant - at 184 n/m.

I have calculated an equation which shows EPE = Fx/2 (the area under the trial data graph is EPE, as it is a force (F) vs extension (x) graph).

On the net I found the equation: u = [tex]\sqrt{Rg/2sin20}[/tex]

R-range
g-gravity


How should I go about solving this? We need to collect data from repeated tests etc, its an investigation.

Thanks a lot! :)
 

Answers and Replies

  • #2
rock.freak667
Homework Helper
6,223
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The energy in the spring is 1/2kx2 which is converted into KE as the mass leaves the rubber band.

so you will have by conservation of energy 1/2kx2 = 1/2 mv2 with v being your initial velocity.
 
  • #3
The energy in the spring is 1/2kx2 which is converted into KE as the mass leaves the rubber band.

so you will have by conservation of energy 1/2kx2 = 1/2 mv2 with v being your initial velocity.


So I shouldn't get the speed at the top of the ramp, so it would be KE + MGH?

What else can I do?
 

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