# moments and forcesWatch

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#1
a uniform horizontal beam of weight 200N and length2.5m is freely hinged at one end to a wall. a rope is attached to the free end of the rope. the other end of the rope is attached to the wall at a point vertically above the beam so that the rope makes an angle of 30 degrees with the verticle. calculate the tension in the rope
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7 months ago
#2
Do you know where to start on the Q? Perhaps an idea on the drawing? Any equations that might be involved, perhaps what concepts might be used? ;-;
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#3
Hi
I did draw a diagram but I dont know how to use it to solve the question. I feel like you have to use moments equation: force * perpendicular distance to the pivot.
(Original post by Callicious)
Do you know where to start on the Q? Perhaps an idea on the drawing? Any equations that might be involved, perhaps what concepts might be used? ;-;
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7 months ago
#4
(Original post by misslaiba)
Hi
I did draw a diagram but I dont know how to use it to solve the question. I feel like you have to use moments equation: force * perpendicular distance to the pivot.
Upload the diagram you've drawn - I'd think about taking moments about the hinge as we don't want to find the forces there.
1
7 months ago
#5
Because its a uniformly distributed load, Tributary length (how much of the beam is supported by the rope) would be half the beam.

Half the beam weighs 100N acting downwards in the vertical direction.

Use trig to find out the resultant diagonal force, you have been given one angle at the top (30*) the other is a right angle (90*)
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#6
hi

(Original post by Muttley79)
Upload the diagram you've drawn - I'd think about taking moments about the hinge as we don't want to find the forces there.
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7 months ago
#7
(Original post by misslaiba)
hi
OK great - now take moments -
clockwise moment, the weight =
anticlockwise moment, the Tension =
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#8
oh!
I thought that uniform means that 200N act downwards directly from the centre???

(Original post by Moments)
Because its a uniformly distributed load, Tributary length (how much of the beam is supported by the rope) would be half the beam.

Half the beam weighs 100N acting downwards in the vertical direction.

Use trig to find out the resultant diagonal force, you have been given one angle at the top (30*) the other is a right angle (90*)
0
7 months ago
#9
(Original post by misslaiba)
oh!
I thought that uniform means that 200N act downwards directly from the centre???
You are right - ignore Moments post. Your diagram is correct, although your 30 degree angle is rather large, but that doesn't matter.
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7 months ago
#10
(Original post by Moments)
Because its a uniformly distributed load, Tributary length (how much of the beam is supported by the rope) would be half the beam.

Half the beam weighs 100N acting downwards in the vertical direction.

Use trig to find out the resultant diagonal force, you have been given one angle at the top (30*) the other is a right angle (90*)
I (semi-)understand your logic, but it is not the approach that the OP will have been taught, nor generic. Let's stick to basic moment taking.
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#11
alright, I think I get it how to do it now.
thanks very much!
(Original post by Muttley79)
OK great - now take moments -
clockwise moment, the weight =
anticlockwise moment, the Tension =
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7 months ago
#12
wait can you explain.
(Original post by misslaiba)
alright, I think I get it how to do it now.
thanks very much!
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7 months ago
#13
(Original post by salimyasin10)
wait can you explain.
The problem is solved by using the principle of moments and take the pivot where the hinge is positioned.
Sum of clockwise moments = Sum of anticlockwise moments
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7 months ago
#14
is the question an A-level question?
(Original post by Eimmanuel)
The problem is solved by using the principle of moments and take the pivot where the hinge is positioned.
Sum of clockwise moments = Sum of anticlockwise moments
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7 months ago
#15
(Original post by salimyasin10)
is the question an A-level question?
It could be.
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7 months ago
#16
k, all im worrying about is that it might be a gcse question.
(Original post by Eimmanuel)
It could be.
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7 months ago
#17
(Original post by salimyasin10)
k, all im worrying about is that it might be a gcse question.
Look at your specs to see if you are required to use any trigonometric ratio to solve the physics problems. If yes, then it can appear or else they can still give you such question but with other extra info.
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#18
Yes it is an a level question
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