Equilibrium problem help

  • #1

Homework Statement


Arlene is to walk across a "high wire" strung horizontally between two buildings 14.0m apart. The sag in the rope when she is at the midpoint is 10.0 degrees. If her mass is 52.0kg , what is the tension in the rope at this point?


Homework Equations


Fnet=ma
a=0 so fnet=0

The Attempt at a Solution


So I know that Fg=9.8*52=509.6 N, and I broke down Ft into Ftx and Fty. sin10=Fty/Ft but I have no idea how to use Fg in that formula to find Ft.
In my notes I have "Ft=(m*g)/(2sinθ) which gives the correct answer, but I don't understand how I got that formula. Can someone explain where it came from/give me some guidance. Why 2sin?
 

Answers and Replies

  • #2
Doc Al
Mentor
45,065
1,375
Since she is in equilibrium, ƩF = 0. In particular, the y-component of the net force must equal zero.

What forces act on her? What are their y-components?
 

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