- #1
Adrian Haddock
- 3
- 0
The questions States.
A uniform plank of weight 120N rests on two stools. a weight of 80N is placed on the plank, midway between the stools calculate
A) the force acting on stool A
B) the force acting on stool B
(Cant add a picture for some reason.)
Plank over length = 4.0m
from left hand edge to stool A = 0.5m
from right hand edge to stool B = 1.0m
The answers in the book state
A)48N
b)72N
I know the plank is in equilibrium so Σ M = 0 and Σ F = 0
I know a moment is F * d
My attempt.
I calculated the centre of mass via moments from the left hand side.
as in (m1*d1 + m2*d2)/m1+m2
so distance of the 80N mass is 1.75m
centre of the uniform plank is 120N at 2m.
put those into the above sum i get the effective centre to be at 1.9m. I think i can say this system is the same as a 200N force acting at 1.9m.
Is this correct?
Do I need to work out fro the over hangs?
The answers i get are Ra = 112N and Rb = 88N
by taking a 200N force acting at 1.9m and taking Moments about stool A...
A uniform plank of weight 120N rests on two stools. a weight of 80N is placed on the plank, midway between the stools calculate
A) the force acting on stool A
B) the force acting on stool B
(Cant add a picture for some reason.)
Plank over length = 4.0m
from left hand edge to stool A = 0.5m
from right hand edge to stool B = 1.0m
The answers in the book state
A)48N
b)72N
I know the plank is in equilibrium so Σ M = 0 and Σ F = 0
I know a moment is F * d
My attempt.
I calculated the centre of mass via moments from the left hand side.
as in (m1*d1 + m2*d2)/m1+m2
so distance of the 80N mass is 1.75m
centre of the uniform plank is 120N at 2m.
put those into the above sum i get the effective centre to be at 1.9m. I think i can say this system is the same as a 200N force acting at 1.9m.
Is this correct?
Do I need to work out fro the over hangs?
The answers i get are Ra = 112N and Rb = 88N
by taking a 200N force acting at 1.9m and taking Moments about stool A...