Ski Jump Problem: Verify if Tangent is <20º

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GriffinHeart
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1. Homework Statement
A ski jumper leaves the end of the slope, make a 35º with the horizontal and the slope making -45º with the horizontal. it has initial velocity of 8m/s. For him not to fall the tangent of the trajectory and the slope at the moment of impact should not be bigger then 20º, please verify if that's the case


2. Homework Equations
x = 8*cos(35)t
y = 8*sen(35)t -(1/2)gt^2




I have this exercise solved, what I'm trying to understand is why we want that y = -x, everything in pink is not in the original "drawing" of the problem



new here so hello everyone ^^
 
Attachments
  • Hand-drawn sketch of a ski jump: a black slope curves down to the right from a takeoff point, with a dashed line at 30 degrees and a horizontal line, marked 45 at the slope. A pink curved trajectory arcs from the takeoff point and falls steeply, with a pink velocity arrow labelled v and angle alpha, and the pink label y = -x.
    fisica.jpg
    8.4 KB · Views: 528
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Welcome to the forums.

The reason why you want y = -x is to do with the fact that they specifiy when horizontal and the slope making -45º with the horizontal. Try drawing yourself a right angled triangle where one of the angles is 45º, by doing so the other one must be 45º, and both non hypotenuse sides are equal in length.

Can you see why this implies y = -x ?
 
Oh ok, took a while to realize that, i guess my own drawing was misleading me, (cause i do a curve for the slope). Now i can see the relation that implies y = -x

so its something like what's in purple in the new picture.

Thanks ^^
 
Attachments
  • Hand-drawn diagram of a ski jump with x and y axes, a black curve for the slope, and a pink curve for a projectile path. Labels show 30 and 45 degree angles, alpha, and y = -x. Purple arrows and lines mark the tangent and the line y = -x.
    fisica.jpg
    13.4 KB · Views: 581