- #1
Dongorgon
- 20
- 0
Hi all, currently having a few issues with understanding a few aspects of questions involving normal reactions at angles. Just an example of where I am going wrong:
'A loft door OA of weight 100N is propped open at 50 degrees to the horizontal by a strut AB. The door is hinged at O. OA=OB=1m.'
To find the force in the strut, it was fairly straightforward. Taking moments about '0';
0.5x100sin(40)=Fsin(115)
Hence F = 35.46...N
However, when trying to calculate the normal reaction at the hinge, I'm truly lost how to consider the situation?
My attempt leads to: R+(35.46...)cos(25)=100
Which gives R as 67.9 N, yet is a wrong answer?! Any help would be much appreciated, thanks,
'A loft door OA of weight 100N is propped open at 50 degrees to the horizontal by a strut AB. The door is hinged at O. OA=OB=1m.'
To find the force in the strut, it was fairly straightforward. Taking moments about '0';
0.5x100sin(40)=Fsin(115)
Hence F = 35.46...N
However, when trying to calculate the normal reaction at the hinge, I'm truly lost how to consider the situation?
My attempt leads to: R+(35.46...)cos(25)=100
Which gives R as 67.9 N, yet is a wrong answer?! Any help would be much appreciated, thanks,
