- #1
John O' Meara
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- 0
Two Ladders 4m and 3m long, respectively,are hinged at their tops (point A) and tied together by a horizontal rope .6m above the floor. The ladders weigh 400N and 300N respectively and the center of gravity of each is at its center. If the floor is frictionless, find
(a) the upward force at the bottom of each ladder
(b) the tension in the rope and
(c) the force that one ladder exerts on the other at point A
(d) If a load of 1000N is now suspended from point A, find the tension in the rope.
Draw the 4m ladder on your left (so your drawing is the same as mine) at an angle of 36.87 degrees to the floor, at the r.h.s. is the 3m ladder at an angle of 53.13 degrees to the floor, this means that the angle at point A is 90 degrees. I can do (a) the answers are 326N and 374N respectively, pointing vertically up ward. (b) Let x be the point where the rope is attached to the 4m ladder , taking moments about x:
-326*.8*1 -400*.8 -300*3.3 + 3.75*F3y + 374*4.2 =0
I get 0=3.75*F3y => F3y =0 => F3x=0 i.e.,no tension in the rope at where it is attached to the 3m ladder.
(c)At point A I'm also at a loss to identify the forces.
Thanks for your time and effort.
(a) the upward force at the bottom of each ladder
(b) the tension in the rope and
(c) the force that one ladder exerts on the other at point A
(d) If a load of 1000N is now suspended from point A, find the tension in the rope.
Draw the 4m ladder on your left (so your drawing is the same as mine) at an angle of 36.87 degrees to the floor, at the r.h.s. is the 3m ladder at an angle of 53.13 degrees to the floor, this means that the angle at point A is 90 degrees. I can do (a) the answers are 326N and 374N respectively, pointing vertically up ward. (b) Let x be the point where the rope is attached to the 4m ladder , taking moments about x:
-326*.8*1 -400*.8 -300*3.3 + 3.75*F3y + 374*4.2 =0
I get 0=3.75*F3y => F3y =0 => F3x=0 i.e.,no tension in the rope at where it is attached to the 3m ladder.
(c)At point A I'm also at a loss to identify the forces.
Thanks for your time and effort.