Yeah! I need the helpz. Textbook is shit, teacher is shit and I can't do jack shit in general. Problem: The weight of a climber and her equipment is 650N. The rope is attactched to the climber and fixked to point where it makes an angle of 20 degrees to the vertical. The contact force R acts on the climber at right angles to the rock face. (i) Use a vector triangle or resolve forces to calculate 1 the tension in the rope 2 the contact force R Thanks in advance
Okay, I don't know a lot about physics, but I can give some tips from what I know to help you. First, the climber's weight is equal to mg (mass*gravitational acceleration), meaning mg is substituted for Weight in your calculations. If I'm not mistaken, Tension should equal mg/cos(angle), or W/cos(20). This is because the angle given is to the vertical instead of horizontal (the angle usually given in one of these problems). Usually it would be mg/sin(angle). R is the Normal force, in this case I think it's defined as mgsin(angle), or Wsin(angle) (instead of the usual mgcos(angle)).
I may be wrong however I feel the tension in the rope is 650N if you remember one of newtons laws states on the lines of 'everything has an equal and opposite reaction'. Meaning that if the climber is stationary the tension needs to be exactly the same as her weight otherwise she would be going somewhere. For the contact force R you need to first draw your vector triangle (right angled triangle with weight acting vertically downwards, contact force acting horizontally towards the climber) and use trig to solve. From your description, in my head the sum you need to do is (650)(tan(20)). Hope this helps at all!
It's simple, draw the vectors in a triangle, then use the formulas to find the tension and contact force. First vector is the gravity+weight, this one goes down. the second one is the climber pushing it in an angle of 20 degrees from the starting point. the last one is the contact force that pushes the climber back to the rock, that should only be a line. It should look like this: Edit: It seems I mixed up the climber's vector, that would be the biggest vector in there, the right one, the left one is the gravity though, but not 650 N Uploaded with ImageShack.us
Yeah, the pic's messed up. The R vector should be the Normal force vector perpendicular to the angled vector (which is the Tension, or "Climber's" vector). Here's a corrected picture I made: The black line at the bottom completing the triangle is meaningless other than to show it as a triangle.
